ldap: prefer LDAP port during initgroups user lookup
The first step of an initgroups request is to lookup the user. When
using the AD provider the Global Catalog will be the preferred source.
But not all LDAP attributes of the user might be replicated to the
Global Catalog and as a result some of the missing attributes might be
removed from the cached user object.
Related to https://pagure.io/SSSD/sssd/issue/2474
Reviewed-by: Jakub Hrozek <firstname.lastname@example.org>
(cherry picked from commit b2352a01f86f7c3d6fa4e405069383df9b1b84cb)