Update default event publisher

In pike, the default publisher is gnocchi. Lets use that
as the default. If you are using collector the override
this to notifier:// instead.

Change-Id: Ic6ba909c873bee801843718cc25974abeda9f857

manifests/agent/notification.pp

@@ -65,7 +65,7 @@
 #   (Optional) A list of publishers to put in event_pipeline.yaml
 #   Add 'notifier://?topic=alarm.all' to the list if you are using Aodh
 #   for alarms.
-#   Defaults to ['notifier://'],
+#   Defaults to ['gnocchi://'],
 #
 class ceilometer::agent::notification (
   $manage_service            = true,
@@ -77,7 +77,7 @@ class ceilometer::agent::notification (
   $messaging_urls            = $::os_service_default,
   $package_ensure            = 'present',
   $manage_event_pipeline     = false,
-  $event_pipeline_publishers = ['notifier://'],
+  $event_pipeline_publishers = ['gnocchi://'],
 ) {
 
   include ::ceilometer::deps

releasenotes/notes/update-default-event-publisher-623aff98f426e60f.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - Update the default event publisher to be gnocchi://. This is the
+    default upstream.

spec/classes/ceilometer_agent_notification_spec.rb

@@ -136,7 +136,7 @@ describe 'ceilometer::agent::notification' do
           "      transformers:",
           "      triggers:",
           "      publishers:",
-          "          - notifier://",
+          "          - gnocchi://",
       ])}
     end