Remove deprecrated [rbac] config group

This PS removes the deprecated [rbac] config group. It was replaced
last release cycle with the [patrole] config group, which has
the exact same options. This is because [patrole] is more user-friendly
and congruent with the project name.

Change-Id: Id1a7af0445bd50f44ddcc4277f952391968726b8
diff --git a/patrole_tempest_plugin/rbac_utils.py b/patrole_tempest_plugin/rbac_utils.py
index 9fa3740..2bb9eed 100644
--- a/patrole_tempest_plugin/rbac_utils.py
+++ b/patrole_tempest_plugin/rbac_utils.py
@@ -107,7 +107,7 @@
             # passing the second boundary before attempting to authenticate.
             # Only sleep if a token revocation occurred as a result of role
             # switching. This will optimize test runtime in the case where
-            # ``[identity] admin_role`` == ``[rbac] rbac_test_role``.
+            # ``[identity] admin_role`` == ``[patrole] rbac_test_role``.
             if not role_already_present:
                 time.sleep(1)
             test_obj.os_primary.auth_provider.set_auth()