[hotfix] Harden TaskExecutorTest#testHeartbeatTimeoutWithJobManager by increasing timeout

In order to check whether the heartbeat manager detects timeouts we wait on the
JobMasterGateway.disconnectTaskManager call which happens asynchronously. In order to harden
the test, we increase the timeout from 50 ms to 500 ms for the timeout call to happen.

flink-runtime/src/test/java/org/apache/flink/runtime/taskexecutor/TaskExecutorTest.java

@@ -199,7 +199,7 @@ public class TaskExecutorTest extends TestLogger {
 					eq(taskManager.getAddress()), eq(taskManagerLocation), eq(jmLeaderId), any(Time.class));
 
 			// the timeout should trigger disconnecting from the JobManager
-			verify(jobMasterGateway, timeout(heartbeatTimeout * 5)).disconnectTaskManager(eq(taskManagerLocation.getResourceID()), any(TimeoutException.class));
+			verify(jobMasterGateway, timeout(heartbeatTimeout * 50L)).disconnectTaskManager(eq(taskManagerLocation.getResourceID()), any(TimeoutException.class));
 
 			// check if a concurrent error occurred
 			testingFatalErrorHandler.rethrowError();