python:gp: Implement client site lookup in site_dn_for_machine()

python:gp: Implement client site lookup in site_dn_for_machine()

This is [MS-GPOL] 3.2.5.1.4 Site Search.

The netr_DsRGetSiteName() needs to run over local rpc, however we do not
have the call implemented in our rpc_server. What netr_DsRGetSiteName()
actually does is an ldap query to get the sitename, we can just do the
same.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15588

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
(cherry picked from commit e4c3c61302b12419f041867b58350f11dc800318)

Autobuild-User(v4-20-test): Jule Anger <janger@samba.org>
Autobuild-Date(v4-20-test): Fri Mar  1 09:01:06 UTC 2024 on atb-devel-224