Use test cluster exclusive in CancellableTasksIT (#67058)

testRemoveBanParentsOnDisconnect disconnects some nodes and leaves the 
cluster in an unhealthy state, which fails other tests. We can reconnect
nodes after that test. However, this commit chooses to run this suite
test-cluster exclusive instead because it is simpler and more stable.

Closes #6652

Author: dnhatn

server/src/internalClusterTest/java/org/elasticsearch/action/admin/cluster/node/tasks/CancellableTasksIT.java

@@ -60,7 +60,6 @@
 import org.elasticsearch.transport.TransportResponseHandler;
 import org.elasticsearch.transport.TransportService;
 import org.junit.After;
-import org.junit.Before;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -83,6 +82,7 @@
 import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.instanceOf;
 
+@ESIntegTestCase.ClusterScope(scope = ESIntegTestCase.Scope.TEST)
 public class CancellableTasksIT extends ESIntegTestCase {
 
     static int idGenerator = 0;
@@ -91,15 +91,6 @@ public class CancellableTasksIT extends ESIntegTestCase {
     static final Map<TestRequest, CountDownLatch> beforeExecuteLatches = ConcurrentCollections.newConcurrentMap();
     static final Map<TestRequest, CountDownLatch> completedLatches = ConcurrentCollections.newConcurrentMap();
 
-    @Before
-    public void resetTestStates() {
-        idGenerator = 0;
-        beforeSendLatches.clear();
-        arrivedLatches.clear();
-        beforeExecuteLatches.clear();
-        completedLatches.clear();
-    }
-
     @After
     public void ensureAllBansRemoved() throws Exception {
         assertBusy(() -> {
@@ -150,7 +141,7 @@ static Set<TestRequest> allowPartialRequest(TestRequest request) throws Exceptio
             beforeSendLatches.get(req).countDown();
         }
         for (TestRequest req : sentRequests) {
-            arrivedLatches.get(req).await();
+            assertTrue(arrivedLatches.get(req).await(60, TimeUnit.SECONDS));
         }
         Set<TestRequest> completedRequests = new HashSet<>();
         for (TestRequest req : randomSubsetOf(sentRequests)) {
@@ -163,7 +154,7 @@ static Set<TestRequest> allowPartialRequest(TestRequest request) throws Exceptio
             beforeExecuteLatches.get(req).countDown();
         }
         for (TestRequest req : completedRequests) {
-            completedLatches.get(req).await();
+            assertTrue(completedLatches.get(req).await(60, TimeUnit.SECONDS));
         }
         return Sets.difference(sentRequests, completedRequests);
     }
@@ -500,7 +491,7 @@ protected void doExecute(Task task, TestRequest request, ActionListener<TestResp
             GroupedActionListener<TestResponse> groupedListener =
                 new GroupedActionListener<>(listener.map(r -> new TestResponse()), subRequests.size() + 1);
             transportService.getThreadPool().generic().execute(ActionRunnable.supply(groupedListener, () -> {
-                beforeExecuteLatches.get(request).await();
+                assertTrue(beforeExecuteLatches.get(request).await(60, TimeUnit.SECONDS));
                 if (((CancellableTask) task).isCancelled()) {
                     throw new TaskCancelledException("Task was cancelled while executing");
                 }
@@ -524,7 +515,7 @@ public void onFailure(Exception e) {
 
                 @Override
                 protected void doRun() throws Exception {
-                    beforeSendLatches.get(subRequest).await();
+                    assertTrue(beforeSendLatches.get(subRequest).await(60, TimeUnit.SECONDS));
                     if (client.getLocalNodeId().equals(subRequest.node.getId()) && randomBoolean()) {
                         try {
                             client.executeLocally(TransportTestAction.ACTION, subRequest, latchedListener);