YARN-7452. Decommissioning node default value to be zero in new YARN UI. Contributed by Vasudevan Skm.

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-ui/src/main/webapp/app/models/cluster-metric.js

@@ -89,7 +89,7 @@ export default DS.Model.extend({
     });
     arr.push({
       label: "Decommissioning",
-      value: this.get("decommissioningNodes")
+      value: this.get("decommissioningNodes") || 0
     });
     arr.push({
       label: "Decomissioned",