AMBARI-3052. After NameNode HA is enabled, hide the button to enable it in Admin > High Availability. (akovalenko via yusaku)

ambari-web/app/views/main/admin/highAvailability_view.js

@@ -25,6 +25,8 @@ App.MainAdminHighAvailabilityView = Em.View.extend({
     this.get('controller').setSecurityStatus();
   },
 
-  isHighAvailabilityEnabled: false //todo: real check
+  isHighAvailabilityEnabled: function () {
+    return !App.HostComponent.find().someProperty('componentName', 'SECONDARY_NAMENODE');
+  }.property()
 
 });