[Profiling] Use CancellableTask internally

With this commit we eagerly cast the task provided to our central
transport action to a CancellableTask so we can simplify cancellation
checks while the action is being executed.

Relates elastic#107037

x-pack/plugin/profiling/src/main/java/org/elasticsearch/xpack/profiling/TransportGetStackTracesAction.java

@@ -149,8 +149,10 @@ public TransportGetStackTracesAction(
     }
 
     @Override
-    protected void doExecute(Task submitTask, GetStackTracesRequest request, ActionListener<GetStackTracesResponse> submitListener) {
+    protected void doExecute(Task task, GetStackTracesRequest request, ActionListener<GetStackTracesResponse> submitListener) {
         licenseChecker.requireSupportedLicense();
+        assert task instanceof CancellableTask;
+        final CancellableTask submitTask = (CancellableTask) task;
         GetStackTracesResponseBuilder responseBuilder = new GetStackTracesResponseBuilder(request);
         Client client = new ParentTaskAssigningClient(this.nodeClient, transportService.getLocalNode(), submitTask);
         if (request.isUserProvidedIndices()) {
@@ -161,7 +163,7 @@ protected void doExecute(Task submitTask, GetStackTracesRequest request, ActionL
     }
 
     private void searchProfilingEvents(
-        Task submitTask,
+        CancellableTask submitTask,
         Client client,
         GetStackTracesRequest request,
         ActionListener<GetStackTracesResponse> submitListener,
@@ -201,7 +203,7 @@ private void searchProfilingEvents(
     }
 
     private void searchGenericEvents(
-        Task submitTask,
+        CancellableTask submitTask,
         Client client,
         GetStackTracesRequest request,
         ActionListener<GetStackTracesResponse> submitListener,
@@ -240,7 +242,7 @@ private void searchGenericEvents(
     }
 
     private void searchGenericEventGroupedByStackTrace(
-        Task submitTask,
+        CancellableTask submitTask,
         Client client,
         GetStackTracesRequest request,
         ActionListener<GetStackTracesResponse> submitListener,
@@ -320,7 +322,7 @@ private void searchGenericEventGroupedByStackTrace(
     }
 
     private void searchEventGroupedByStackTrace(
-        Task submitTask,
+        CancellableTask submitTask,
         Client client,
         GetStackTracesRequest request,
         ActionListener<GetStackTracesResponse> submitListener,
@@ -432,7 +434,7 @@ The same stacktraces may come from different hosts (eventually from different da
     }
 
     private ActionListener<SearchResponse> handleEventsGroupedByStackTrace(
-        Task submitTask,
+        CancellableTask submitTask,
         Client client,
         GetStackTracesResponseBuilder responseBuilder,
         ActionListener<GetStackTracesResponse> submitListener,
@@ -471,12 +473,12 @@ private static long getAggValueAsLong(SearchResponse searchResponse, String fiel
     }
 
     private void retrieveStackTraces(
-        Task submitTask,
+        CancellableTask submitTask,
         Client client,
         GetStackTracesResponseBuilder responseBuilder,
         ActionListener<GetStackTracesResponse> submitListener
     ) {
-        if (submitTask instanceof CancellableTask c && c.notifyIfCancelled(submitListener)) {
+        if (submitTask.notifyIfCancelled(submitListener)) {
             return;
         }
         List<String> eventIds = new ArrayList<>(responseBuilder.getStackTraceEvents().keySet());
@@ -554,7 +556,7 @@ static <T> List<List<T>> sliced(List<T> c, int slices) {
 
     private class StackTraceHandler {
         private final AtomicInteger expectedResponses;
-        private final Task submitTask;
+        private final CancellableTask submitTask;
         private final ClusterState clusterState;
         private final Client client;
         private final GetStackTracesResponseBuilder responseBuilder;
@@ -568,7 +570,7 @@ private class StackTraceHandler {
         private final Map<String, HostMetadata> hostMetadata;
 
         private StackTraceHandler(
-            Task submitTask,
+            CancellableTask submitTask,
             ClusterState clusterState,
             Client client,
             GetStackTracesResponseBuilder responseBuilder,
@@ -691,15 +693,15 @@ public void mayFinish() {
     }
 
     private void retrieveStackTraceDetails(
-        Task submitTask,
+        CancellableTask submitTask,
         ClusterState clusterState,
         Client client,
         GetStackTracesResponseBuilder responseBuilder,
         List<String> stackFrameIds,
         List<String> executableIds,
         ActionListener<GetStackTracesResponse> submitListener
     ) {
-        if (submitTask instanceof CancellableTask c && c.notifyIfCancelled(submitListener)) {
+        if (submitTask.notifyIfCancelled(submitListener)) {
             return;
         }
         List<Index> stackFrameIndices = resolver.resolve(