Remove graduated test and fixtures libraries

The config fixture is now part of oslo.config and the other ones are
part of oslotest. Let's remove them!

Change-Id: I90ab87772bda17a3f7872c41db869c4e278cf57c

tests/unit/test_eventlet_backdoor.py

@@ -21,11 +21,11 @@ import errno
 import socket
 
 import eventlet
+from oslo.config import fixture as config
 from oslotest import base as test_base
 from oslotest import moxstubout
 
 from openstack.common import eventlet_backdoor
-from openstack.common.fixture import config
 
 
 class BackdoorPortTest(test_base.BaseTestCase):

tests/unit/test_periodic.py

@@ -19,10 +19,10 @@ Unit Tests for periodic_task decorator and PeriodicTasks class.
 """
 
 import mock
+from oslo.config import fixture as config
 from oslotest import base as test_base
 from testtools import matchers
 
-from openstack.common.fixture import config
 from openstack.common import periodic_task
 
 

tests/unit/test_service.py

@@ -31,12 +31,12 @@ import traceback
 import eventlet
 from eventlet import event
 import mock
+from oslo.config import fixture as config
 from oslotest import base as test_base
 from oslotest import moxstubout
 from six.moves import mox
 
 from openstack.common import eventlet_backdoor
-from openstack.common.fixture import config
 from openstack.common import log as logging
 from openstack.common import service