Clean up namespace class resources via addClassResourceCleanup

This patch cleans up namespace class resources via addClassResourceCleanup.

Change-Id: I4507b56856f20bfc1adbfdaafc92a9ff66ff6f4b
diff --git a/patrole_tempest_plugin/tests/api/image/test_image_namespace_tags_rbac.py b/patrole_tempest_plugin/tests/api/image/test_image_namespace_tags_rbac.py
index 8e2bc49..ecf2ec2 100644
--- a/patrole_tempest_plugin/tests/api/image/test_image_namespace_tags_rbac.py
+++ b/patrole_tempest_plugin/tests/api/image/test_image_namespace_tags_rbac.py
@@ -39,11 +39,9 @@
         cls.namespace = cls.namespaces_client.create_namespace(
             namespace=data_utils.rand_name(
                 cls.__name__ + '-namespace'))['namespace']
-
-    @classmethod
-    def resource_cleanup(cls):
-        cls.namespaces_client.delete_namespace(cls.namespace)
-        super(NamespaceTagsRbacTest, cls).resource_cleanup()
+        cls.addClassResourceCleanup(
+            cls.namespaces_client.delete_namespace,
+            cls.namespace)
 
     def _create_namespace_tag(self, multiple=False):
         tag_count = 2 if multiple else 1