Stop usage of "IPA.messages" in Web UI "utils" tests
    
    IPA doesn't provide "messages" anymore.
    But actually ones are no needed for these tests.
    
    Fixes: https://pagure.io/freeipa/issue/7559
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Petr Vobornik <pvoborni@redhat.com>