Remove  RBAC test_volume_list_image_metadata test case

Remove the test_volume_list_image_metadata test case as it duplicates with
test_list_volumes_details_image_metadata in test_volume_metadata_rbac.py.  Also,
test_volume_list_image_metadata does not test list image metadata correctly
since the volume_image_metadata attribute has never been created in the first
place.

Change-Id: I07c3971f5bdb4255105612538e58c79d69daa691
diff --git a/patrole_tempest_plugin/tests/api/volume/test_volume_basic_crud_rbac.py b/patrole_tempest_plugin/tests/api/volume/test_volume_basic_crud_rbac.py
index 1bd87d2..61532c6 100644
--- a/patrole_tempest_plugin/tests/api/volume/test_volume_basic_crud_rbac.py
+++ b/patrole_tempest_plugin/tests/api/volume/test_volume_basic_crud_rbac.py
@@ -62,11 +62,3 @@
         with self.rbac_utils.override_role(self):
             self.volumes_client.update_volume(self.volume['id'],
                                               name=update_name)
-
-    @rbac_rule_validation.action(
-        service="cinder",
-        rule="volume_extension:volume_image_metadata")
-    @decorators.idempotent_id('3d48ca91-f02b-4616-a69d-4a8b296c8529')
-    def test_volume_list_image_metadata(self):
-        with self.rbac_utils.override_role(self):
-            self.volumes_client.list_volumes(detail=True)