Configure aodh coordination backend_url

Add ability to configure aodh coordination backend_url from
coordination_backend:redis pillar if defined

Related-Prod: PROD-29126

Change-Id: I5f9b98c472be31e6344b438515d4075a959c2c1d
diff --git a/tests/pillar/server_cluster.sls b/tests/pillar/server_cluster.sls
index 9cf1c07..300094c 100644
--- a/tests/pillar/server_cluster.sls
+++ b/tests/pillar/server_cluster.sls
@@ -60,6 +60,19 @@
         enabled: true
         strategy: ENCRYPT
         secret_key: secret
+    coordination_backend:
+      url: redis://127.0.0.1/test
+      engine: redis
+      redis:
+        password: pswd
+        user: openstack
+        db: '0'
+        sentinel:
+          host: 127.0.0.1
+          master_name: master_1
+          fallback:
+            - host: 127.0.1.1
+            - host: 127.0.2.1
 apache:
   server:
     enabled: true