Cloudkitty: remove oslo_messaging_notifications config

Cloudkitty doesn't use notification, cause there is no references to
notification system in Cloudkitty code base.

Change-Id: I17d276452d3861360feb6030f8622542cc455128

ansible/roles/cloudkitty/templates/cloudkitty.conf.j2

@@ -30,10 +30,6 @@ lock_path = /var/lib/cloudkitty/tmp
 collector = {{ cloudkitty_collector_backend }}
 services = compute,image{% if enable_cinder | bool %},volume{% endif %},network.bw.out,network.bw.in,network.floating
 
-[oslo_messaging_notifications]
-driver = messagingv2
-topics = notifications
-
 [keystone_fetcher]
 keystone_version = 3
 auth_section = keystone_authtoken