imds: suppress or downgrade log messages

imds: suppress or downgrade log messages

Other places that read credentials filer out ENXIO:
$ journalctl -b -u systemd-imds-early-network.service -o short-monotonic --no-hostname --no-pager -p warning
[    5.477675] systemd-imdsd[473]: Failed to read credential 'imds.vendor', ignoring: No such device or address
[    5.477687] systemd-imdsd[473]: Failed to read credential 'imds.vendor_token', ignoring: No such device or address
[    5.477693] systemd-imdsd[473]: Failed to read credential 'imds.refresh_header_name', ignoring: No such device or address
[    5.477699] systemd-imdsd[473]: Failed to read credential 'imds.data_url', ignoring: No such device or address
[    5.477704] systemd-imdsd[473]: Failed to read credential 'imds.data_url_suffix', ignoring: No such device or address
[    5.477710] systemd-imdsd[473]: Failed to read credential 'imds.token_header_name', ignoring: No such device or address
[    5.477714] systemd-imdsd[473]: Failed to read credential 'imds.extra_header', ignoring: No such device or address
[    5.477720] systemd-imdsd[473]: Failed to read credential 'imds.extra_header2', ignoring: No such device or address
[    5.477730] systemd-imdsd[473]: Failed to read credential 'imds.extra_header3', ignoring: No such device or address
[    5.477736] systemd-imdsd[473]: Failed to read credential 'imds.extra_header4', ignoring: No such device or address
[    5.477742] systemd-imdsd[473]: Failed to read credential 'imds.extra_header5', ignoring: No such device or address
[    5.477747] systemd-imdsd[473]: Failed to read credential 'imds.extra_header6', ignoring: No such device or address
[    5.477751] systemd-imdsd[473]: Failed to read credential 'imds.extra_header7', ignoring: No such device or address
[    5.477757] systemd-imdsd[473]: Failed to read credential 'imds.extra_header8', ignoring: No such device or address
[    5.477763] systemd-imdsd[473]: Failed to read credential 'imds.extra_header9', ignoring: No such device or address
[    5.477768] systemd-imdsd[473]: Failed to read credential 'imds.extra_header10', ignoring: No such device or address
[    5.477774] systemd-imdsd[473]: Failed to read credential 'imds.extra_header11', ignoring: No such device or address
[    5.477779] systemd-imdsd[473]: Failed to read credential 'imds.extra_header12', ignoring: No such device or address
[    5.477784] systemd-imdsd[473]: Failed to read credential 'imds.extra_header13', ignoring: No such device or address
[    5.477789] systemd-imdsd[473]: Failed to read credential 'imds.extra_header14', ignoring: No such device or address
[    5.477799] systemd-imdsd[473]: Failed to read credential 'imds.extra_header15', ignoring: No such device or address
[    5.477804] systemd-imdsd[473]: Failed to read credential 'imds.extra_header16', ignoring: No such device or address
[    5.477810] systemd-imdsd[473]: Failed to read credential 'imds.extra_header17', ignoring: No such device or address
[    5.477815] systemd-imdsd[473]: Failed to read credential 'imds.extra_header18', ignoring: No such device or address
[    5.477820] systemd-imdsd[473]: Failed to read credential 'imds.extra_header19', ignoring: No such device or address
[    5.477825] systemd-imdsd[473]: Failed to read credential 'imds.extra_header20', ignoring: No such device or address
[    5.477830] systemd-imdsd[473]: Failed to read credential 'imds.extra_header21', ignoring: No such device or address
[    5.477835] systemd-imdsd[473]: Failed to read credential 'imds.extra_header22', ignoring: No such device or address
[    5.477840] systemd-imdsd[473]: Failed to read credential 'imds.extra_header23', ignoring: No such device or address
[    5.477845] systemd-imdsd[473]: Failed to read credential 'imds.extra_header24', ignoring: No such device or address
[    5.477851] systemd-imdsd[473]: Failed to read credential 'imds.extra_header25', ignoring: No such device or address
[    5.477856] systemd-imdsd[473]: Failed to read credential 'imds.extra_header26', ignoring: No such device or address
[    5.477865] systemd-imdsd[473]: Failed to read credential 'imds.extra_header27', ignoring: No such device or address
[    5.477869] systemd-imdsd[473]: Failed to read credential 'imds.extra_header28', ignoring: No such device or address
[    5.477874] systemd-imdsd[473]: Failed to read credential 'imds.extra_header29', ignoring: No such device or address
[    5.477881] systemd-imdsd[473]: Failed to read credential 'imds.extra_header30', ignoring: No such device or address
[    5.477885] systemd-imdsd[473]: Failed to read credential 'imds.extra_header31', ignoring: No such device or address
[    5.477890] systemd-imdsd[473]: Failed to read credential 'imds.extra_header32', ignoring: No such device or address
[    5.477896] systemd-imdsd[473]: Failed to read credential 'imds.extra_header33', ignoring: No such device or address
[    5.477901] systemd-imdsd[473]: Failed to read credential 'imds.extra_header34', ignoring: No such device or address
[    5.477906] systemd-imdsd[473]: Failed to read credential 'imds.extra_header35', ignoring: No such device or address
[    5.477913] systemd-imdsd[473]: Failed to read credential 'imds.extra_header36', ignoring: No such device or address
[    5.477917] systemd-imdsd[473]: Failed to read credential 'imds.extra_header37', ignoring: No such device or address
[    5.477922] systemd-imdsd[473]: Failed to read credential 'imds.extra_header38', ignoring: No such device or address
[    5.477931] systemd-imdsd[473]: Failed to read credential 'imds.extra_header39', ignoring: No such device or address
[    5.477935] systemd-imdsd[473]: Failed to read credential 'imds.extra_header40', ignoring: No such device or address
[    5.477940] systemd-imdsd[473]: Failed to read credential 'imds.extra_header41', ignoring: No such device or address
[    5.477945] systemd-imdsd[473]: Failed to read credential 'imds.extra_header42', ignoring: No such device or address
[    5.477951] systemd-imdsd[473]: Failed to read credential 'imds.extra_header43', ignoring: No such device or address
[    5.477956] systemd-imdsd[473]: Failed to read credential 'imds.extra_header44', ignoring: No such device or address
[    5.477962] systemd-imdsd[473]: Failed to read credential 'imds.extra_header45', ignoring: No such device or address
[    5.477967] systemd-imdsd[473]: Failed to read credential 'imds.extra_header46', ignoring: No such device or address
[    5.477972] systemd-imdsd[473]: Failed to read credential 'imds.extra_header47', ignoring: No such device or address
[    5.477978] systemd-imdsd[473]: Failed to read credential 'imds.extra_header48', ignoring: No such device or address
[    5.477982] systemd-imdsd[473]: Failed to read credential 'imds.extra_header49', ignoring: No such device or address
[    5.477988] systemd-imdsd[473]: Failed to read credential 'imds.extra_header50', ignoring: No such device or address
[    5.477995] systemd-imdsd[473]: Failed to read credential 'imds.extra_header51', ignoring: No such device or address
[    5.477999] systemd-imdsd[473]: Failed to read credential 'imds.extra_header52', ignoring: No such device or address
[    5.478022] systemd-imdsd[473]: Failed to read credential 'imds.extra_header53', ignoring: No such device or address
[    5.478028] systemd-imdsd[473]: Failed to read credential 'imds.extra_header54', ignoring: No such device or address
[    5.478033] systemd-imdsd[473]: Failed to read credential 'imds.extra_header55', ignoring: No such device or address
[    5.478039] systemd-imdsd[473]: Failed to read credential 'imds.extra_header56', ignoring: No such device or address
[    5.478044] systemd-imdsd[473]: Failed to read credential 'imds.extra_header57', ignoring: No such device or address
[    5.478050] systemd-imdsd[473]: Failed to read credential 'imds.extra_header58', ignoring: No such device or address
[    5.478055] systemd-imdsd[473]: Failed to read credential 'imds.extra_header59', ignoring: No such device or address
[    5.478060] systemd-imdsd[473]: Failed to read credential 'imds.extra_header60', ignoring: No such device or address
[    5.478066] systemd-imdsd[473]: Failed to read credential 'imds.extra_header61', ignoring: No such device or address
[    5.478071] systemd-imdsd[473]: Failed to read credential 'imds.extra_header62', ignoring: No such device or address
[    5.478079] systemd-imdsd[473]: Failed to read credential 'imds.extra_header63', ignoring: No such device or address
[    5.478086] systemd-imdsd[473]: Failed read IPv4 address from credential 'imds.address_ipv4', ignoring: No such device or address
[    5.478091] systemd-imdsd[473]: Failed read IPv6 address from credential 'imds.address_ipv6', ignoring: No such device or address
[    5.478097] systemd-imdsd[473]: Failed to read credential 'imds.key_hostname', ignoring: No such device or address
[    5.478102] systemd-imdsd[473]: Failed to read credential 'imds.key_region', ignoring: No such device or address
[    5.478107] systemd-imdsd[473]: Failed to read credential 'imds.key_zone', ignoring: No such device or address
[    5.478113] systemd-imdsd[473]: Failed to read credential 'imds.key_ipv4_public', ignoring: No such device or address
[    5.478119] systemd-imdsd[473]: Failed to read credential 'imds.key_ipv6_public', ignoring: No such device or address
[    5.478123] systemd-imdsd[473]: Failed to read credential 'imds.key_ssh_key', ignoring: No such device or address
[    5.478128] systemd-imdsd[473]: Failed to read credential 'imds.key_userdata', ignoring: No such device or address
[    5.478134] systemd-imdsd[473]: Failed to read credential 'imds.key_userdata_base', ignoring: No such device or address
[    5.478137] systemd-imdsd[473]: Failed to read credential 'imds.key_userdata_base64', ignoring: No such device or address