### 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
/*
     * This field holds the result of the task in the remoteCoordinationDiagnosisTask field above. The field is accessed
     * (reads/writes) from multiple threads, but is only ever reassigned on a single thread (the cluster change event thread).
     */
    volatile AtomicReference<RemoteMasterHealthResult> remoteCoordinationDiagnosisResult = null;
    /**
     * This is the amount of time that we wait before scheduling a remote request to gather diagnostic information. It is not
     * user-configurable, but is non-final so that integration tests don't have to waste 10 seconds.
     */
    
    static TimeValue remoteRequestInitialDelay = new TimeValue(10, TimeUnit.SECONDS);
    private static final Logger logger = LogManager.getLogger(CoordinationDiagnosticsService.class);
    /**
     * This is the default amount of time we look back to see if we have had a master at all, before moving on with other checks
     */
    public static final Setting<TimeValue> NODE_HAS_MASTER_LOOKUP_TIMEFRAME_SETTING = Setting.timeSetting(
        "health.master_history.has_master_lookup_timeframe",
        new TimeValue(30, TimeUnit.SECONDS),
        new TimeValue(1, TimeUnit.SECONDS),
        Setting.Property.NodeScope
    );
    /**
     * This is the number of times that it is not OK to have a master go null. This many transitions or more will be reported as a problem.
     */
    public static final Setting<Integer> NO_MASTER_TRANSITIONS_THRESHOLD_SETTING = Setting.intSetting(
        "health.master_history.no_master_transitions_threshold",
        4,
        0,
        Setting.Property.NodeScope
    );