ipatests: Make sure we re-kinit as admin before adding the disabledipauser
    
    When we add the disabledipauser during the setup class part of the
    BaseTestLegacyClient, we need to make sure that we re-kinit admin
    since we do ntpsync with the AD just before that, which can render
    the previous ticket invalid.
    
    Reviewed-By: Nathaniel McCallum <npmccallum@redhat.com>