fix(ecs): update application caching agent to get appname from Moniker

Author: piradeepk

clouddriver-ecs/src/main/java/com/netflix/spinnaker/clouddriver/ecs/provider/agent/ApplicationCachingAgent.java

@@ -83,7 +83,7 @@ protected List<Application> getItems(AmazonECS ecs, ProviderCache providerCache)
     Map<String, Map<String, Collection<String>>> appRelationships = new HashMap<>();
 
     for (Service service : services) {
-      String applicationKey = service.getApplicationName();
+      String applicationKey = service.getMoniker().getApp();
       String serviceKey =
           Keys.getServiceKey(service.getAccount(), service.getRegion(), service.getServiceName());