Move test decorators to common

services and extension decorators are based on CONF and needed by
Tempest only, so moving them to tempest.common.
Since a few plugnis use them today, use debtcollector to avoid
breaking all dependencies.

Change-Id: Ibd52153d00b8e60fb8c89e38d94e358ddc787251
diff --git a/tempest/api/volume/test_volumes_backup.py b/tempest/api/volume/test_volumes_backup.py
index 1f91db6..f2d8801 100644
--- a/tempest/api/volume/test_volumes_backup.py
+++ b/tempest/api/volume/test_volumes_backup.py
@@ -17,11 +17,11 @@
 from testtools import matchers
 
 from tempest.api.volume import base
+from tempest.common import utils
 from tempest.common import waiters
 from tempest import config
 from tempest.lib.common.utils import data_utils
 from tempest.lib import decorators
-from tempest import test
 
 CONF = config.CONF
 
@@ -97,7 +97,7 @@
                         matchers.ContainsAll(metadata.items()))
 
     @decorators.idempotent_id('07af8f6d-80af-44c9-a5dc-c8427b1b62e6')
-    @test.services('compute')
+    @utils.services('compute')
     def test_backup_create_attached_volume(self):
         """Test backup create using force flag.
 
@@ -119,7 +119,7 @@
         self.assertEqual(backup_name, backup['name'])
 
     @decorators.idempotent_id('2a8ba340-dff2-4511-9db7-646f07156b15')
-    @test.services('image')
+    @utils.services('image')
     def test_bootable_volume_backup_and_restore(self):
         # Create volume from image
         img_uuid = CONF.compute.image_ref