Tests: Fix failing tests in test_ipalib/test_frontend
    
    Some tests in ipatests/test_ipalib/test_frontend.py are failing due to changes
    related to thin client implementation. Providing fix for:
      ipa.test_ipalib.test_frontend.test_Attribute.test_init
      ipa.test_ipalib.test_frontend.test_LocalOrRemote.test_run
    
    https://fedorahosted.org/freeipa/ticket/6188
    
    Reviewed-By: Milan Kubik <mkubik@redhat.com>