s3:rpc_server: Remove dead code

Signed-off-by: Samuel Cabrero <scabrero@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

Autobuild-User(master): Samuel Cabrero <scabrero@samba.org>
Autobuild-Date(master): Fri Mar 20 17:11:28 UTC 2020 on sn-devel-184
