auth: let auth logging prefer user_info->orig_client.{account,domain}_name if available

auth: let auth logging prefer user_info->orig_client.{account,domain}_name if available

The optional user_info->orig_client.{account,domain}_name are
the once really used by the client and should be used in
audit logging. But we still fallback to
user_info->client.{account,domain}_name.

This will be important for the next commit.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13879

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