Enable instance usage audit only when ceilometer is enabled

This patch disables periodic compute.instance.exists
notifications when designate is enabled.

Related-Bug: #2049503
Change-Id: I39fe2db9182de23c1df814d911eec15e86317702

ansible/roles/nova-cell/templates/nova.conf.j2

@@ -26,7 +26,7 @@ compute_driver = libvirt.LibvirtDriver
 # Though my_ip is not used directly, lots of other variables use $my_ip
 my_ip = {{ api_interface_address }}
 
-{% if enable_ceilometer | bool or enable_designate | bool %}
+{% if enable_ceilometer | bool %}
 instance_usage_audit = True
 instance_usage_audit_period = hour
 {% if enable_watcher | bool %}

ansible/roles/nova/templates/nova.conf.j2

@@ -16,7 +16,7 @@ allow_resize_to_same_host = true
 # Though my_ip is not used directly, lots of other variables use $my_ip
 my_ip = {{ api_interface_address }}
 
-{% if enable_ceilometer | bool or enable_designate | bool %}
+{% if enable_ceilometer | bool %}
 instance_usage_audit = True
 instance_usage_audit_period = hour
 {% endif %}

releasenotes/notes/disable-usage-audit-notifications-6e63588bdcc48603.yaml

+---
+fixes:
+  - |
+    Fixes enabled usage audit notifications when they
+    are not needed. See `LP##2049503
+    <https://bugs.launchpad.net/kolla-ansible/+bug/2049503>`__.