Fix testCancelRequestWhenFailingFetchingPages (elastic#106447)

If we proceed without waiting for pages, we might cancel the main 
request before starting the data-node request. As a result, the exchange
sinks on data-nodes won't be removed until the inactive_timeout elapses,
which is longer than the assertBusy timeout.

Closes elastic#106443

x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/action/EsqlActionTaskIT.java

@@ -330,7 +330,6 @@ private void assertCancelled(ActionFuture<EsqlQueryResponse> response) throws Ex
      * Ensure that when some exchange requests fail, we cancel the ESQL request, and complete all
      * exchange sinks with the failure, despite having outstanding pages in the buffer.
      */
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/106443")
     public void testCancelRequestWhenFailingFetchingPages() throws Exception {
         String coordinator = internalCluster().startCoordinatingOnlyNode(Settings.EMPTY);
         String dataNode = internalCluster().startDataOnlyNode();
@@ -368,6 +367,9 @@ protected void doRun() throws Exception {
             request.pragmas(randomPragmas());
             PlainActionFuture<EsqlQueryResponse> future = new PlainActionFuture<>();
             client.execute(EsqlQueryAction.INSTANCE, request, future);
+            ExchangeService exchangeService = internalCluster().getInstance(ExchangeService.class, dataNode);
+            boolean waitedForPages;
+            final String sessionId;
             try {
                 List<TaskInfo> foundTasks = new ArrayList<>();
                 assertBusy(() -> {
@@ -381,19 +383,25 @@ protected void doRun() throws Exception {
                     assertThat(tasks, hasSize(1));
                     foundTasks.addAll(tasks);
                 });
-                String sessionId = foundTasks.get(0).taskId().toString();
-                ExchangeService exchangeService = internalCluster().getInstance(ExchangeService.class, dataNode);
+                sessionId = foundTasks.get(0).taskId().toString();
                 assertTrue(fetchingStarted.await(1, TimeUnit.MINUTES));
                 ExchangeSinkHandler exchangeSink = exchangeService.getSinkHandler(sessionId);
-                if (randomBoolean()) {
-                    // do not fail exchange requests when we have some pages
+                waitedForPages = randomBoolean();
+                if (waitedForPages) {
+                    // do not fail exchange requests until we have some pages
                     assertBusy(() -> assertThat(exchangeSink.bufferSize(), greaterThan(0)));
                 }
             } finally {
                 allowedFetching.countDown();
             }
             Exception failure = expectThrows(Exception.class, () -> future.actionGet().close());
             assertThat(failure.getMessage(), containsString("failed to fetch pages"));
+            // If we proceed without waiting for pages, we might cancel the main request before starting the data-node request.
+            // As a result, the exchange sinks on data-nodes won't be removed until the inactive_timeout elapses, which is
+            // longer than the assertBusy timeout.
+            if (waitedForPages == false) {
+                exchangeService.finishSinkHandler(sessionId, failure);
+            }
         } finally {
             transportService.clearAllRules();
         }