remove breaking backward compatible changes

Signed-off-by: Kaushal Kumar <[email protected]>

Author: kaushalmahi12

CHANGELOG.md

@@ -113,7 +113,6 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Stop processing search requests when _msearch request is cancelled ([#17005](https://github.com/opensearch-project/OpenSearch/pull/17005))
 - Fix GRPC AUX_TRANSPORT_PORT and SETTING_GRPC_PORT settings and remove lingering HTTP terminology ([#17037](https://github.com/opensearch-project/OpenSearch/pull/17037))
 - [WLM] Add WLM support for search scroll API ([#16981](https://github.com/opensearch-project/OpenSearch/pull/16981))
-- Fix exists queries on nested flat_object fields throws exception ([#16803](https://github.com/opensearch-project/OpenSearch/pull/16803))
 - Use OpenSearch version to deserialize remote custom metadata([#16494](https://github.com/opensearch-project/OpenSearch/pull/16494))
 
 ### Security

server/src/main/java/org/opensearch/action/search/TransportSearchScrollAction.java

@@ -39,9 +39,7 @@
 import org.opensearch.core.action.ActionListener;
 import org.opensearch.core.common.io.stream.Writeable;
 import org.opensearch.tasks.Task;
-import org.opensearch.threadpool.ThreadPool;
 import org.opensearch.transport.TransportService;
-import org.opensearch.wlm.QueryGroupTask;
 
 /**
  * Perform the search scroll
@@ -53,32 +51,24 @@ public class TransportSearchScrollAction extends HandledTransportAction<SearchSc
     private final ClusterService clusterService;
     private final SearchTransportService searchTransportService;
     private final SearchPhaseController searchPhaseController;
-    private final ThreadPool threadPool;
 
     @Inject
     public TransportSearchScrollAction(
         TransportService transportService,
         ClusterService clusterService,
         ActionFilters actionFilters,
         SearchTransportService searchTransportService,
-        SearchPhaseController searchPhaseController,
-        ThreadPool threadPool
+        SearchPhaseController searchPhaseController
     ) {
         super(SearchScrollAction.NAME, transportService, actionFilters, (Writeable.Reader<SearchScrollRequest>) SearchScrollRequest::new);
         this.clusterService = clusterService;
         this.searchTransportService = searchTransportService;
         this.searchPhaseController = searchPhaseController;
-        this.threadPool = threadPool;
     }
 
     @Override
     protected void doExecute(Task task, SearchScrollRequest request, ActionListener<SearchResponse> listener) {
         try {
-
-            if (task instanceof QueryGroupTask) {
-                ((QueryGroupTask) task).setQueryGroupId(threadPool.getThreadContext());
-            }
-
             ParsedScrollId scrollId = TransportSearchHelper.parseScrollId(request.scrollId());
             Runnable action;
             switch (scrollId.getType()) {