CVE-2022-38023 docs-xml/smbdotconf: change 'reject md5 servers' default to yes

CVE-2022-38023 docs-xml/smbdotconf: change 'reject md5 servers' default to yes

AES is supported by Windows >= 2008R2 and Samba >= 4.0 so there's no
reason to allow md5 servers by default.

Note the change in netlogon_creds_cli_context_global() is only cosmetic,
but avoids confusion while reading the code. Check with:

 git show -U35 libcli/auth/netlogon_creds_cli.c

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15240

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>