inlcude AD primary group in user filter, if a group is selected. 

fixes #12190

How to test?
- configure User Filter in the LDAP Wizard and select a group
- on AD, the resulting filter should look like ```(&(|(objectclass=person))(|(|((memberof=CN=Domain Users,CN=Users,DC=madder,DC=owncloud,DC=bzoc)(primaryGroupID=513)))(|((memberof=CN=Wolfpack 8,OU=packs,DC=madder,DC=owncloud,DC=bzoc)(primaryGroupID=968988)```(2 selected groups)
- on OpenLDAP the ```(primaryGroupID=XXX)``` part should not show up!
- in the User list users should appear, that have the selected group  as primary, but are not regular member of any of those selected