Fix SearchStatesIT.testCanMatch (elastic#120046)

Adding back the old style free request to fix CCS BwC situations where we need to proxy requests exactly as is and can't drop the technically redundant original indices.

closes elastic#118718

Author: original-brownbear

muted-tests.yml

@@ -400,9 +400,6 @@ tests:
 - class: org.elasticsearch.xpack.restart.FullClusterRestartIT
   method: testWatcherWithApiKey {cluster=UPGRADED}
   issue: https://github.com/elastic/elasticsearch/issues/119396
-- class: org.elasticsearch.upgrades.SearchStatesIT
-  method: testCanMatch
-  issue: https://github.com/elastic/elasticsearch/issues/118718
 - class: org.elasticsearch.search.profile.dfs.DfsProfilerIT
   method: testProfileDfs
   issue: https://github.com/elastic/elasticsearch/issues/119711

server/src/main/java/org/elasticsearch/action/search/SearchTransportService.java

@@ -13,10 +13,12 @@
 import org.apache.logging.log4j.Logger;
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.action.ActionListenerResponseHandler;
+import org.elasticsearch.action.IndicesRequest;
 import org.elasticsearch.action.OriginalIndices;
 import org.elasticsearch.action.admin.cluster.node.tasks.cancel.CancelTasksRequest;
 import org.elasticsearch.action.admin.cluster.node.tasks.get.TransportGetTaskAction;
 import org.elasticsearch.action.support.ChannelActionListener;
+import org.elasticsearch.action.support.IndicesOptions;
 import org.elasticsearch.client.internal.OriginSettingClient;
 import org.elasticsearch.client.internal.node.NodeClient;
 import org.elasticsearch.cluster.node.DiscoveryNode;
@@ -350,6 +352,38 @@ private static class ClearScrollContextsRequest extends TransportRequest {
         }
     }
 
+    static class SearchFreeContextRequest extends ScrollFreeContextRequest implements IndicesRequest {
+        private final OriginalIndices originalIndices;
+
+        SearchFreeContextRequest(StreamInput in) throws IOException {
+            super(in);
+            originalIndices = OriginalIndices.readOriginalIndices(in);
+        }
+
+        @Override
+        public void writeTo(StreamOutput out) throws IOException {
+            super.writeTo(out);
+            OriginalIndices.writeOriginalIndices(originalIndices, out);
+        }
+
+        @Override
+        public String[] indices() {
+            if (originalIndices == null) {
+                return null;
+            }
+            return originalIndices.indices();
+        }
+
+        @Override
+        public IndicesOptions indicesOptions() {
+            if (originalIndices == null) {
+                return null;
+            }
+            return originalIndices.indicesOptions();
+        }
+
+    }
+
     public static class SearchFreeContextResponse extends TransportResponse {
 
         private static final SearchFreeContextResponse FREED = new SearchFreeContextResponse(true);
@@ -400,12 +434,13 @@ public static void registerRequestHandler(TransportService transportService, Sea
         );
 
         // TODO: remove this handler once the lowest compatible version stops using it
-        transportService.registerRequestHandler(FREE_CONTEXT_ACTION_NAME, freeContextExecutor, in -> {
-            var res = new ScrollFreeContextRequest(in);
-            // this handler exists for BwC purposes only, we don't need the original indices to free the context
-            OriginalIndices.readOriginalIndices(in);
-            return res;
-        }, freeContextHandler);
+        // this handler exists for BwC purposes only, we don't need the original indices to free the context
+        transportService.registerRequestHandler(
+            FREE_CONTEXT_ACTION_NAME,
+            freeContextExecutor,
+            SearchFreeContextRequest::new,
+            freeContextHandler
+        );
         TransportActionProxy.registerProxyAction(transportService, FREE_CONTEXT_ACTION_NAME, false, SearchFreeContextResponse::readFrom);
 
         transportService.registerRequestHandler(