ipatests: fix wrong condition in xfail_context for auto private grp
    
    The tests
    TestNonPosixAutoPrivateGroup::test_idoverride_with_auto_private_group
    and
    TestPosixAutoPrivateGroup::test_gidnumber_not_corresponding_existing_group
    are expected to fail until SSSD fixes issues 5988 and 5989.
    They currently define an xfail_context with a condition based on
    sssd version but that condition is wrong (as of today, no version
    of sssd provides the fix).
    
    Remove the wrong condition so that the test is always expected to fail.
    
    Fixes: https://pagure.io/freeipa/issue/9141
    Reviewed-By: Anuja More <amore@redhat.com>