s3:passdb: use cli_credentials_set_kerberos_state() for trusts in pdb_get_trust_crede...

s3:passdb: use cli_credentials_set_kerberos_state() for trusts in pdb_get_trust_credentials()

Trust accounts can only use kerberos when contacting other AD domains,
using NTLMSSP will fail.

At the same time it doesn't make sense to try kerberos for NT4 domains,
still NTLMSSP will fail, but the callers has to deal with that
case and just fallback to an anonymous SMB connection.

In all cases we should be able to use NETLOGON SCHANNEL
over any anonymous smb or tcp transport.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12598

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