Remove unused dependency to config module

Auth module unit tests import and mock config, which is not
needed anymore since the auth module has been made independent
from config. Cleaning up the unused dependency in preparation
to migration to tempest-lib.

Change-Id: Iedcd2fa7713409743b1b4b9f460481608796d491
diff --git a/tempest/tests/test_auth.py b/tempest/tests/test_auth.py
index f54ff4f..eb63b30 100644
--- a/tempest/tests/test_auth.py
+++ b/tempest/tests/test_auth.py
@@ -19,12 +19,10 @@
 from oslotest import mockpatch
 
 from tempest import auth
-from tempest import config
 from tempest import exceptions
 from tempest.services.identity.v2.json import token_client as v2_client
 from tempest.services.identity.v3.json import token_client as v3_client
 from tempest.tests import base
-from tempest.tests import fake_config
 from tempest.tests import fake_credentials
 from tempest.tests import fake_http
 from tempest.tests import fake_identity
@@ -46,8 +44,6 @@
 
     def setUp(self):
         super(BaseAuthTestsSetUp, self).setUp()
-        self.useFixture(fake_config.ConfigFixture())
-        self.stubs.Set(config, 'TempestConfigPrivate', fake_config.FakePrivate)
         self.fake_http = fake_http.fake_httplib2(return_type=200)
         self.stubs.Set(auth, 'get_credentials', fake_get_credentials)
         self.auth_provider = self._auth(self.credentials,