Revert "Set tempest_roles=admin for contrail enabled environment"

This reverts commit 1128bfe5cf320b5da8676baf4f59e11e1222121a.

Change-Id: I4b3316aff788b3fcdb9d34d2598a9e0229d9aa37
diff --git a/_modules/runtest/tempest_sections/auth.py b/_modules/runtest/tempest_sections/auth.py
index be7e38d..aae2cbd 100644
--- a/_modules/runtest/tempest_sections/auth.py
+++ b/_modules/runtest/tempest_sections/auth.py
@@ -53,16 +53,10 @@
         # Barbican may be enabled in several components like nova,glance,cinder.
         # Look for nova only as it is core openstack service and present on each installation.
         # Assume if barbican is enabled in nova, its integration enabled globally.
-        roles = []
-        contrail_enabled = conditions.BaseRule('opencontrail.control.enabled',
-                                               'eq', True, multiple='any')
-        if contrail_enabled:
-            roles.append("admin")
+
         c = conditions.BaseRule('nova.controller.enabled', 'eq', True)
         if self.get_item_when_condition_match('nova.controller.barbican.enabled', c):
-            roles.append("creator")
-        if roles:
-            return ', '.join(roles)
+            return 'creator'
 
     @property
     def test_accounts_file(self):