CVE-2022-38023 s3:rpc_server/netlogon: Avoid unnecessary loadparm_context allocations

CVE-2022-38023 s3:rpc_server/netlogon: Avoid unnecessary loadparm_context allocations

After s3 and s4 rpc servers merge the loadparm_context is available in
the dcesrv_context structure.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15240

Signed-off-by: Samuel Cabrero <scabrero@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>
Autobuild-User(master): Andreas Schneider <asn@cryptomilk.org>
Autobuild-Date(master): Mon Jan  9 15:17:14 UTC 2023 on sn-devel-184

(cherry picked from commit 56837f3d3169a02d0d92bd085d9c8250415ce29b)

Autobuild-User(v4-15-test): Jule Anger <janger@samba.org>
Autobuild-Date(v4-15-test): Mon Jan 23 10:01:41 UTC 2023 on sn-devel-184