ipatests: Do not require group name resolution for the non-posix tests
    
    In the non-posix tests on the legacy clients, the testuser does not
    belong to the testgroup (since this is represented by the NIS
    group membership).
    
    Relax the regular expression check for the output of the id testuser.
    
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>