Relax message check in test_create_host_with_ip
    
    On Travis CI, the DNS update in test case test_create_host_with_ip may fail
    with different error messages. Relax the error message check and just
    check that the test case is hitting a DNS update failure.
    
    This fixes a flaky test case on CI.
    
    Closes: https://pagure.io/freeipa/issue/7447
    Signed-off-by: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>