Enable sending events to notification bus by default

According to [1] in order to Aodh event alarms work notifier publisher
should be set with special topic (alarm.all by default).

[1] https://docs.openstack.org/aodh/latest/contributor/event-alarm.html

Change-Id: I2719ad7b071ff68ccc1072972aabca3d0f3168d8
Related-Prod: https://mirantis.jira.com/browse/PROD-20427
diff --git a/aodh/server/cluster.yml b/aodh/server/cluster.yml
index 0a590cf..2ff4ea9 100644
--- a/aodh/server/cluster.yml
+++ b/aodh/server/cluster.yml
@@ -4,6 +4,8 @@
 - system.haproxy.proxy.listen.openstack.aodh
 - system.keepalived.cluster.instance.openstack_telemetry_vip
 parameters:
+  _param:
+    openstack_event_alarm_topic: alarm.all
   aodh:
     server:
       enabled: true
@@ -13,6 +15,7 @@
       debug: false
       verbose: true
       region: ${_param:openstack_region}
+      event_alarm_topic: ${_param:openstack_event_alarm_topic}
       database:
         engine: "mysql"
         host: ${_param:openstack_database_address}
diff --git a/aodh/server/single.yml b/aodh/server/single.yml
index eba3fc1..df4be81 100644
--- a/aodh/server/single.yml
+++ b/aodh/server/single.yml
@@ -1,2 +1,8 @@
 classes:
 - service.aodh.server.single
+parameters:
+  _param:
+    openstack_event_alarm_topic: alarm.all
+  aodh:
+    server:
+      event_alarm_topic: ${_param:openstack_event_alarm_topic}
diff --git a/ceilometer/server/backend/default.yml b/ceilometer/server/backend/default.yml
index 542314c..071e4a1 100644
--- a/ceilometer/server/backend/default.yml
+++ b/ceilometer/server/backend/default.yml
@@ -2,6 +2,8 @@
 - service.ceilometer.server.publisher.gnocchi
 - service.ceilometer.server.publisher.panko
 parameters:
+  _param:
+    openstack_event_alarm_topic: alarm.all
   # gnocchi and panko are default backends for Ceilometer since Pike
   # they are incompatible with any legacy database publisher backends
   ceilometer:
@@ -12,3 +14,7 @@
       publisher:
         default:
           enabled: false
+        event_alarm_notifier:
+          enabled: true
+          url: "notifier://?topic=${_param:openstack_event_alarm_topic}"
+          publish_event: true