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/scenario/test_aggregates_basic_ops.py b/tempest/scenario/test_aggregates_basic_ops.py
index 25227be..9ff6227 100644
--- a/tempest/scenario/test_aggregates_basic_ops.py
+++ b/tempest/scenario/test_aggregates_basic_ops.py
@@ -14,10 +14,10 @@
 #    under the License.
 
 from tempest.common import tempest_fixtures as fixtures
+from tempest.common import utils
 from tempest.lib.common.utils import data_utils
 from tempest.lib import decorators
 from tempest.scenario import manager
-from tempest import test
 
 
 class TestAggregatesBasicOps(manager.ScenarioTest):
@@ -97,7 +97,7 @@
 
     @decorators.idempotent_id('cb2b4c4f-0c7c-4164-bdde-6285b302a081')
     @decorators.attr(type='slow')
-    @test.services('compute')
+    @utils.services('compute')
     def test_aggregate_basic_ops(self):
         self.useFixture(fixtures.LockFixture('availability_zone'))
         az = 'foo_zone'