### 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/transport/TransportService.java
throw new IllegalArgumentException("system property [" + PERMIT_HANDSHAKES_FROM_INCOMPATIBLE_BUILDS_KEY + "] must not be set");
        }
        assert Version.CURRENT.major == Version.V_7_0_0.major + 1; 
    }
    private record UnregisterChildTransportResponseHandler<T extends TransportResponse> (
        Releasable unregisterChildNode,
        TransportResponseHandler<T> handler,
        String action
    ) implements TransportResponseHandler<T> {
        @Override
        public void handleResponse(T response) {
            unregisterChildNode.close();
            handler.handleResponse(response);
        }
        @Override
        public void handleException(TransportException exp) {
            unregisterChildNode.close();
            handler.handleException(exp);
        }
        @Override
        public String executor() {
            return handler.executor();
        }
        @Override
        public T read(StreamInput in) throws IOException {
            return handler.read(in);
        }
    }
}