Remove undocumented action.master.force_local setting (#29351)

`action.master.force_local` was only ever used internally and never documented. It was one of those settings that were
automatically added to a tribe node, to make sure that cluster state read operations would work locally rather than failing when trying to forward the request to the master (as the tribe node never had a master).

Given that we recently removed the tribe node, we can also remove this setting.

server/src/main/java/org/elasticsearch/action/support/master/TransportMasterNodeReadAction.java

@@ -24,8 +24,6 @@ import org.elasticsearch.action.support.ActionFilters;
 import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
 import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.settings.Setting;
-import org.elasticsearch.common.settings.Setting.Property;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.TransportService;
@@ -39,11 +37,6 @@ import java.util.function.Supplier;
 public abstract class TransportMasterNodeReadAction<Request extends MasterNodeReadRequest<Request>, Response extends ActionResponse>
         extends TransportMasterNodeAction<Request, Response> {
 
-    public static final Setting<Boolean> FORCE_LOCAL_SETTING =
-        Setting.boolSetting("action.master.force_local", false, Property.NodeScope);
-
-    private final boolean forceLocal;
-
     protected TransportMasterNodeReadAction(Settings settings, String actionName, TransportService transportService,
                                             ClusterService clusterService, ThreadPool threadPool, ActionFilters actionFilters,
                                             IndexNameExpressionResolver indexNameExpressionResolver, Supplier<Request> request) {
@@ -61,7 +54,6 @@ public abstract class TransportMasterNodeReadAction<Request extends MasterNodeRe
                                             IndexNameExpressionResolver indexNameExpressionResolver, Supplier<Request> request) {
         super(settings, actionName, checkSizeLimit, transportService, clusterService, threadPool, actionFilters,
             indexNameExpressionResolver,request);
-        this.forceLocal = FORCE_LOCAL_SETTING.get(settings);
     }
 
     protected TransportMasterNodeReadAction(Settings settings, String actionName, boolean checkSizeLimit, TransportService transportService,
@@ -69,11 +61,10 @@ public abstract class TransportMasterNodeReadAction<Request extends MasterNodeRe
                                             Writeable.Reader<Request> request, IndexNameExpressionResolver indexNameExpressionResolver) {
         super(settings, actionName, checkSizeLimit, transportService, clusterService, threadPool, actionFilters, request,
             indexNameExpressionResolver);
-        this.forceLocal = FORCE_LOCAL_SETTING.get(settings);
     }
 
     @Override
     protected final boolean localExecute(Request request) {
-        return forceLocal || request.local();
+        return request.local();
     }
 }

server/src/main/java/org/elasticsearch/common/settings/ClusterSettings.java

@@ -22,7 +22,6 @@ import org.elasticsearch.action.admin.indices.close.TransportCloseIndexAction;
 import org.elasticsearch.action.search.TransportSearchAction;
 import org.elasticsearch.action.support.AutoCreateIndex;
 import org.elasticsearch.action.support.DestructiveOperations;
-import org.elasticsearch.action.support.master.TransportMasterNodeReadAction;
 import org.elasticsearch.bootstrap.BootstrapSettings;
 import org.elasticsearch.client.Client;
 import org.elasticsearch.client.transport.TransportClient;
@@ -373,7 +372,6 @@ public final class ClusterSettings extends AbstractScopedSettings {
                     Node.NODE_INGEST_SETTING,
                     Node.NODE_ATTRIBUTES,
                     Node.NODE_LOCAL_STORAGE_SETTING,
-                    TransportMasterNodeReadAction.FORCE_LOCAL_SETTING,
                     AutoCreateIndex.AUTO_CREATE_INDEX_SETTING,
                     BaseRestHandler.MULTI_ALLOW_EXPLICIT_INDEX,
                     ClusterName.CLUSTER_NAME_SETTING,