Description of problem:
SSSD uses the following LDAP query to detect if the AD Global Catalog (GC)
server can be used to retrieve POSIX attributes:

'(|(&(uidNumber=*)(objectClass=user))(&(gidNumber=*)(objectClass=group)))'

The filter is used with a sizelimit of '1' but AD is not properly honoring the
sizelimit. This issue is tracked in BZ #1582975.

The other issue is that this query should only go to the Global Catalog server
but with the current version of SSSD we do see this query also going to regular
AD DCs.

Version-Release number of selected component (if applicable):
sssd-1.16.0-19.el7.x86_64

Steps to Reproduce:
1. Configure SSSD with AD provider.
2. Create an AD account with POSIX attributes
3. Login into the SSSD client using this account

Actual results:
The LDAP query listed above goes to a regular AD DC. Because of the issue
reported in BZ #1582975 it might happen that SSSD runs into a timeout and the
next server is contacted. This might end up in an infinite loop until the
search can be completed.


Expected results:
LDAP query goes only to AD GC server.

Additional info:
This is a possible regression.