smbXsrv_client: handle NAME_NOT_FOUND from smb2srv_client_connection_{pass,drop}()

smbXsrv_client: handle NAME_NOT_FOUND from smb2srv_client_connection_{pass,drop}()

If we get NT_STATUS_OBJECT_NOT_FOUND from smb2srv_client_connection_{pass,drop}()
we should just keep the connection and overwrite the stale record in
smbXsrv_client_global.tdb. It's basically a race with serverid_exists()
and a process that doesn't cleanly teardown.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15200

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