Similarly to https://github.com/elastic/elasticsearch/pull/97873 but for request handlers: let's stop passing around strings and looking these things up by name on each request when we could just pass around the `Executor` itself.
server/src/main/java/org/elasticsearch/action/support/master/TransportMasterNodeAction.java
import org.elasticsearch.index.IndexNotFoundException;
import org.elasticsearch.node.NodeClosedException;
import org.elasticsearch.reservedstate.ActionWithReservedState;
import org.elasticsearch.tasks.CancellableTask;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.tasks.TaskCancelledException;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.transport.ConnectTransportException;
import org.elasticsearch.transport.RemoteTransportException;
import org.elasticsearch.transport.TransportException;
import org.elasticsearch.transport.TransportService;
import java.util.Optional;
import java.util.concurrent.Executor;
import java.util.function.Predicate;
import static org.elasticsearch.core.Strings.format;
/**
 * A base class for operations that needs to be performed on the master node.
 */
public abstract class TransportMasterNodeAction<Request extends MasterNodeRequest<Request>, Response extends ActionResponse> extends
    HandledTransportAction<Request, Response>
    implements
        ActionWithReservedState<Request> {
    private static final Logger logger = LogManager.getLogger(TransportMasterNodeAction.class);
    protected final ThreadPool threadPool;
    protected final TransportService transportService;
    protected final ClusterService clusterService;
    protected final IndexNameExpressionResolver indexNameExpressionResolver;
    private final Writeable.Reader<Response> responseReader;
    protected final Executor executor;
    /**