Do not use nova.test in placement.test_requestlog

The tests are very straightforward and do not require any of the setup
and fixtures that nova.test.NoDBTestCase supplies. Also, in the future
of placement extraction we don't want the dependecy.

Partially implements blueprint placement-extract

Change-Id: Ib917601a61b896e7ed86e0cd189c442ffaf883b3

nova/tests/unit/api/openstack/placement/test_requestlog.py

@@ -13,13 +13,13 @@
 """Tests for the placement request log middleware."""
 
 import mock
+import testtools
 import webob
 
 from nova.api.openstack.placement import requestlog
-from nova import test
 
 
-class TestRequestLog(test.NoDBTestCase):
+class TestRequestLog(testtools.TestCase):
 
     @staticmethod
     @webob.dec.wsgify