### 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
assertThat(tracerA.responseReceived.get(), equalTo(1));
            assertThat(tracerA.responseSent.get(), equalTo(0));
            assertThat(tracerB.requestsReceived.get(), equalTo(1));
            assertThat(tracerB.requestsSent.get(), equalTo(0));
            assertThat(tracerB.responseReceived.get(), equalTo(0));
            assertThat(tracerB.responseSent.get(), equalTo(1));
        });
        try {
            submitRequest(serviceB, nodeA, ACTION, TransportRequest.Empty.INSTANCE, EmptyTransportResponseHandler.INSTANCE_SAME).get();
        } catch (ExecutionException e) {
            assertThat(e.getCause(), instanceOf(ElasticsearchException.class));
            assertThat(ExceptionsHelper.unwrapCause(e.getCause()).getMessage(), equalTo("simulated"));
        }
        
        assertBusy(() -> {
            assertThat(tracerA.requestsReceived.get(), equalTo(1));
            assertThat(tracerA.requestsSent.get(), equalTo(1));
            assertThat(tracerA.responseReceived.get(), equalTo(1));
            assertThat(tracerA.responseSent.get(), equalTo(1));
            assertThat(tracerB.requestsReceived.get(), equalTo(1));
            assertThat(tracerB.requestsSent.get(), equalTo(1));
            assertThat(tracerB.responseReceived.get(), equalTo(1));
            assertThat(tracerB.responseSent.get(), equalTo(1));
        });
        
        try {
            submitRequest(serviceA, nodeA, ACTION, TransportRequest.Empty.INSTANCE, EmptyTransportResponseHandler.INSTANCE_SAME).get();
        } catch (ExecutionException e) {
            assertThat(e.getCause(), instanceOf(ElasticsearchException.class));
            assertThat(ExceptionsHelper.unwrapCause(e.getCause()).getMessage(), equalTo("simulated"));