### Description

The `sendRequest` method is asynchronous and notifies a 
`TransportResponseHandler` when it completes the excecution
(successfully or unsuccessfully). 

When opening the connection we only catch `NodeNotConnectedException`
( https://github.com/elastic/elasticsearch/blob/main/server/src/main/java/org/elasticsearch/transport/TransportService.java#L719 ) which is currently fine as no implementations
throw other type of exception however, it'd be best to catch `Exception` here
so the `handler` gets notified of potential exceptions (as opposed to the caller
having to `try/catch` the call to `sendRequest`)
test/framework/src/main/java/org/elasticsearch/transport/AbstractSimpleTransportTestCase.java
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.ActionListenerResponseHandler;
import org.elasticsearch.action.StepListener;
import org.elasticsearch.action.support.PlainActionFuture;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.common.io.stream.BytesStreamOutput;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.logging.Loggers;
import org.elasticsearch.common.network.CloseableChannel;
import org.elasticsearch.common.network.NetworkAddress;
import org.elasticsearch.common.network.NetworkUtils;
import org.elasticsearch.common.settings.ClusterSettings;
import org.elasticsearch.common.settings.Setting;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.transport.BoundTransportAddress;
import org.elasticsearch.common.transport.TransportAddress;
import org.elasticsearch.common.util.concurrent.AbstractRunnable;
import org.elasticsearch.common.util.concurrent.ConcurrentCollections;
import org.elasticsearch.core.IOUtils;
import org.elasticsearch.core.Nullable;
import org.elasticsearch.core.Releasable;
import org.elasticsearch.core.SuppressForbidden;
import org.elasticsearch.core.TimeValue;
import org.elasticsearch.mocksocket.MockServerSocket;
import org.elasticsearch.node.Node;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.test.ESTestCase;
import org.elasticsearch.test.MockLogAppender;
import org.elasticsearch.test.VersionUtils;