winbind: remove legacy flags fallback

winbind: remove legacy flags fallback

Some very old NT4 DCs might have not returned the account flags filled in. This
shouldn't be a problem anymore. Additionally, on a typical domain member server,
this request is (and can only be) send to the primary domain, so this will not
work with accounts from trusted domains.

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Thu Jan 21 22:56:20 UTC 2021 on sn-devel-184