[VNC schema] Remove multi-tenancy for unit tests

By default the unit test start a fake VNC api server with multi-tenancy
enabled. As there is no emulation of keystone service, the admin request
on API fail to get resource hidden to users.

Change-Id: Ia28bbf6a9d6258f66aedb9b83cad80111ae3fe52
Closes-bug: #1598255

src/config/schema-transformer/test/test_case.py

@@ -54,6 +54,14 @@ def wait_to_delete_object(self, obj_class, obj_name):
 
 class STTestCase(test_common.TestCase):
 
+    @classmethod
+    def setUpClass(cls):
+        extra_config = [
+            ('DEFAULTS', 'multi_tenancy', 'False'),
+            ('DEFAULTS', 'multi_tenancy_with_rbac', 'False'),
+        ]
+        super(STTestCase, cls).setUpClass(extra_config_knobs=extra_config)
+
     def _class_str(self):
         return str(self.__class__).strip('<class ').strip('>').strip("'")