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/nodes/TransportNodesAction.java
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.ActionListenerResponseHandler;
import org.elasticsearch.action.FailedNodeException;
import org.elasticsearch.action.support.ActionFilters;
import org.elasticsearch.action.support.CancellableFanOut;
import org.elasticsearch.action.support.HandledTransportAction;
import org.elasticsearch.action.support.ThreadedActionListener;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.service.ClusterService;
import org.elasticsearch.common.collect.Iterators;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.Writeable;
import org.elasticsearch.common.util.concurrent.EsExecutors;
import org.elasticsearch.core.CheckedConsumer;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.transport.TransportChannel;
import org.elasticsearch.transport.TransportRequest;
import org.elasticsearch.transport.TransportRequestHandler;
import org.elasticsearch.transport.TransportRequestOptions;
import org.elasticsearch.transport.TransportService;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.Executor;
import static org.elasticsearch.core.Strings.format;
public abstract class TransportNodesAction<