### 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
AtomicReference<Scheduler.Cancellable> cancellableReference
    ) {
        DiscoveryNode masterEligibleNode = getMasterEligibleNodes().stream().findAny().orElse(null);
        try {
            cancellableReference.set(
                fetchCoordinationDiagnostics(
                    masterEligibleNode,
                    responseConsumer.andThen(rescheduleDiagnosticsFetchConsumer(responseConsumer, cancellableReference))
                )
            );
        } catch (EsRejectedExecutionException e) {
            if (e.isExecutorShutdown()) {
                logger.trace("Not rescheduling request for cluster coordination info because this node is being shutdown", e);
            } else {
                throw e;
            }
        }
    }
    /**
     * This wraps the responseConsumer in a Consumer that will run rescheduleDiagnosticsFetchConsumer() after responseConsumer has
     * completed, adding the resulting Cancellable to cancellableReference.
     * @param responseConsumer The response consumer to be wrapped
     * @param cancellableReference The Cancellable reference to assign the current Cancellable for this polling attempt
     * @return A wrapped Consumer that will run fetchCoordinationDiagnostics()
     */
    private Consumer<RemoteMasterHealthResult> rescheduleDiagnosticsFetchConsumer(
        Consumer<RemoteMasterHealthResult> responseConsumer,
        AtomicReference<Scheduler.Cancellable> cancellableReference
    ) {
        return response -> {