### 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`)
server/src/main/java/org/elasticsearch/cluster/coordination/CoordinationDiagnosticsService.java
return new RemoteMasterHealthResult(masterEligibleNode, null, e);
                }
            }
        );
    }
    /**
     * This method connects to masterEligibleNode and sends it a transport request for a response of type R. The response or exception
     * are transformed into a common type T with responseToResultFunction or exceptionToResultFunction, and then consumed by
     * responseConsumer. This method is meant to be used when there is potentially no elected master node, so it first calls
     * connectToNode before sending the request.
     * @param masterEligibleNode        The master eligible node to be queried, or null if we do not yet know of a master eligible node.
     *                                  If this is null, the responseConsumer will be given a null response
     * @param responseConsumer          The consumer of the transformed response
     * @param transportActionType       The ActionType for the transport action
     * @param transportActionRequest    The ActionRequest to be sent
     * @param responseTransformationFunction A function that converts a response or exception to the response type expected by the
     *                                       responseConsumer
     * @return A Cancellable for the task that is scheduled to fetch the remote information
     */
    private <R extends ActionResponse, T> Scheduler.Cancellable sendTransportRequest(
        @Nullable DiscoveryNode masterEligibleNode,
        Consumer<T> responseConsumer,
        ActionType<R> transportActionType,
        ActionRequest transportActionRequest,
        BiFunction<R, Exception, T> responseTransformationFunction
    ) {
        StepListener<Releasable> connectionListener = new StepListener<>();
        StepListener<R> fetchRemoteResultListener = new StepListener<>();
        long startTime = System.nanoTime();
        connectionListener.whenComplete(releasable -> {