ipatests: remove additional check for failed units.
    
    On RHEL tests are randomly failing because of this check
    and the test doesn't need to check this.
    
    Related : https://pagure.io/freeipa/issue/9108
    
    Signed-off-by: Anuja More <amore@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>