Fix Ceilometer tests config options

Ceilometer tempest tests have been moved to plugin but config options
were renamed as same were registered by Tempest also.

Now Tempest is removing ceilometer tests and related config options
- I0775bcc15dc9cbae6e075fe92f44b5f6c9b9d5d2
we need to fix their name back to original one to avoid backward incompatibility.

Congress use those in ceilometer integration tests and will break if we
do not rename those back to original one.

Change-Id: Id10cd260d12eba5b4f4d7798dee64fc62a92eb1c
Depends-On: I0775bcc15dc9cbae6e075fe92f44b5f6c9b9d5d2
diff --git a/ceilometer/tests/tempest/api/base.py b/ceilometer/tests/tempest/api/base.py
index 103a123..81c53d6 100644
--- a/ceilometer/tests/tempest/api/base.py
+++ b/ceilometer/tests/tempest/api/base.py
@@ -49,7 +49,7 @@
     @classmethod
     def skip_checks(cls):
         super(BaseTelemetryTest, cls).skip_checks()
-        if not CONF.service_available.ceilometer_plugin:
+        if not CONF.service_available.ceilometer:
             raise cls.skipException("Ceilometer support is required")
 
     @classmethod