tempest_plugin: drop telemetry decorator

Since [1], 'telemetry' service does not exist and Tempest plugin is now
broken:

InvalidServiceTag: Invalid service tag
Details: telemetry is not a valid service

This patch update the test_object_storage_telemetry_middleware test to
match with the Tempest cleanup.

[1] https://github.com/openstack/tempest/commit/e4796f8de446aaaafa83902d1fb2d613331436cf

Change-Id: I2ae71b722826a4e377a4926c943d1dbce3b1ed9f
diff --git a/ceilometer/tests/tempest/scenario/test_object_storage_telemetry_middleware.py b/ceilometer/tests/tempest/scenario/test_object_storage_telemetry_middleware.py
index 4bb287d..f4a1b1d 100644
--- a/ceilometer/tests/tempest/scenario/test_object_storage_telemetry_middleware.py
+++ b/ceilometer/tests/tempest/scenario/test_object_storage_telemetry_middleware.py
@@ -139,7 +139,7 @@
         return obj_name
 
     @test.idempotent_id('6d6b88e5-3e38-41bc-b34a-79f713a6cb85')
-    @test.services('object_storage', 'telemetry')
+    @test.services('object_storage')
     def test_swift_middleware_notifies(self):
         container_name = self.create_container()
         obj_name = self.upload_object_to_container(container_name)