YARN-9594. Fix missing break statement in ContainerScheduler#handle. Contributed by lujie.

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/scheduler/ContainerScheduler.java

@@ -190,6 +190,7 @@ public class ContainerScheduler extends AbstractService implements
       startPendingContainers(maxOppQueueLength <= 0);
       metrics.setQueuedContainers(queuedOpportunisticContainers.size(),
           queuedGuaranteedContainers.size());
+      break;
     default:
       LOG.error("Unknown event arrived at ContainerScheduler: "
           + event.toString());