uidgid: fix users without primary group
    
    This fixes three user entries (vdsm, jbosson-agent, hacluster)
    which are listed without any primary group ID.
    They all have a related standalone group, thus the table was
    only missing the link between them.
    
    Ref: https://src.fedoraproject.org/rpms/vdsm/blob/f22/f/vdsm.spec#_8
    Ref: https://src.fedoraproject.org/rpms/pacemaker/blob/f36/f/pacemaker.spec#_6