Revert "Master node disconnect (#132023)"

This reverts commit 656a7a9.

Author: joshua-adams-1

server/src/internalClusterTest/java/org/elasticsearch/cluster/coordination/NodeJoiningIT.java

@@ -19,10 +19,8 @@
 import org.elasticsearch.action.support.SubscribableListener;
 import org.elasticsearch.action.support.ThreadedActionListener;
 import org.elasticsearch.client.internal.Client;
-import org.elasticsearch.cluster.ClusterChangedEvent;
 import org.elasticsearch.cluster.ClusterName;
 import org.elasticsearch.cluster.ClusterState;
-import org.elasticsearch.cluster.ClusterStateListener;
 import org.elasticsearch.cluster.ClusterStatePublicationEvent;
 import org.elasticsearch.cluster.ClusterStateUpdateTask;
 import org.elasticsearch.cluster.LocalMasterServiceTask;
@@ -41,7 +39,6 @@
 import org.elasticsearch.cluster.routing.allocation.AllocationService;
 import org.elasticsearch.cluster.service.ClusterApplier;
 import org.elasticsearch.cluster.service.ClusterApplierService;
-import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.cluster.service.MasterService;
 import org.elasticsearch.cluster.service.MasterServiceTaskQueue;
 import org.elasticsearch.cluster.version.CompatibilityVersions;
@@ -193,7 +190,6 @@ public class Coordinator extends AbstractLifecycleComponent implements ClusterSt
     private final NodeHealthService nodeHealthService;
     private final List<PeerFinderListener> peerFinderListeners;
     private final LeaderHeartbeatService leaderHeartbeatService;
-    private final ClusterService clusterService;
 
     /**
      * @param nodeName The name of the node, used to name the {@link java.util.concurrent.ExecutorService} of the {@link SeedHostsResolver}.
@@ -222,8 +218,7 @@ public Coordinator(
         LeaderHeartbeatService leaderHeartbeatService,
         PreVoteCollector.Factory preVoteCollectorFactory,
         CompatibilityVersions compatibilityVersions,
-        FeatureService featureService,
-        ClusterService clusterService
+        FeatureService featureService
     ) {
         this.settings = settings;
         this.transportService = transportService;
@@ -333,7 +328,6 @@ public Coordinator(
         this.peerFinderListeners.add(clusterBootstrapService);
         this.leaderHeartbeatService = leaderHeartbeatService;
         this.compatibilityVersions = compatibilityVersions;
-        this.clusterService = clusterService;
     }
 
     /**
@@ -668,57 +662,11 @@ private void handleJoinRequest(JoinRequest joinRequest, ActionListener<Void> joi
         transportService.connectToNode(joinRequest.getSourceNode(), new ActionListener<>() {
             @Override
             public void onResponse(Releasable response) {
-                SubscribableListener
-                    // Validates the join request: can the remote node deserialize our cluster state and does it respond to pings?
-                    .<Void>newForked(l -> validateJoinRequest(joinRequest, l))
-
-                    // Adds the joining node to the cluster state
-                    .<Void>andThen(l -> processJoinRequest(joinRequest, l.delegateResponse((ll, e) -> {
-                        // #ES-11449
-                        if (e instanceof FailedToCommitClusterStateException) {
-                            // The commit failed (i.e. master is failing over) but this does not imply that the join has actually failed:
-                            // the next master may have already accepted the state that we just published and will therefore include the
-                            // joining node in its future states too. Thus we need to wait for the next committed state before we know the
-                            // eventual outcome, and we need to wait for that before we can release (our ref to) the connection and complete
-                            // the listener.
-
-                            // NB we are on the master update thread here at the end of processing the failed cluster state update, so this
-                            // all happens before any cluster state update that re-elects a master
-                            assert ThreadPool.assertCurrentThreadPool(MasterService.MASTER_UPDATE_THREAD_NAME);
-
-                            final ClusterStateListener clusterStateListener = new ClusterStateListener() {
-                                @Override
-                                public void clusterChanged(ClusterChangedEvent event) {
-                                    final var discoveryNodes = event.state().nodes();
-                                    // Keep the connection open until the next committed state
-                                    if (discoveryNodes.getMasterNode() != null) {
-                                        // Remove this listener to avoid memory leaks
-                                        clusterService.removeListener(this);
-                                        if (discoveryNodes.nodeExists(joinRequest.getSourceNode().getId())) {
-                                            ll.onResponse(null);
-                                        } else {
-                                            ll.onFailure(e);
-                                        }
-                                    }
-                                }
-                            };
-                            clusterService.addListener(clusterStateListener);
-                            clusterStateListener.clusterChanged(
-                                new ClusterChangedEvent(
-                                    "Checking if another master has been elected since "
-                                        + joinRequest.getSourceNode().getName()
-                                        + " attempted to join cluster",
-                                    clusterService.state(),
-                                    clusterService.state()
-                                )
-                            );
-                        } else {
-                            ll.onFailure(e);
-                        }
-                    })))
-
-                    // Whatever the outcome, release (our ref to) the connection we just opened and notify the joining node.
-                    .addListener(ActionListener.runBefore(joinListener, () -> Releasables.close(response)));
+                validateJoinRequest(
+                    joinRequest,
+                    ActionListener.runBefore(joinListener, () -> Releasables.close(response))
+                        .delegateFailure((l, ignored) -> processJoinRequest(joinRequest, l))
+                );
             }
 
             @Override