### 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
ConnectionProfile.Builder builder = new ConnectionProfile.Builder();
            builder.addConnections(
                1,
                TransportRequestOptions.Type.BULK,
                TransportRequestOptions.Type.PING,
                TransportRequestOptions.Type.RECOVERY,
                TransportRequestOptions.Type.REG,
                TransportRequestOptions.Type.STATE
            );
            try (Transport.Connection connection = openConnection(serviceA, node, builder.build())) {
                assertEquals(connection.getVersion(), version);
            }
        }
    }
    public void testKeepAlivePings() throws Exception {
        assumeTrue("only tcp transport has keep alive pings", serviceA.getOriginalTransport() instanceof TcpTransport);
        TcpTransport originalTransport = (TcpTransport) serviceA.getOriginalTransport();
        ConnectionProfile defaultProfile = ConnectionProfile.buildDefaultConnectionProfile(Settings.EMPTY);
        ConnectionProfile connectionProfile = new ConnectionProfile.Builder(defaultProfile).setPingInterval(TimeValue.timeValueMillis(50))
            .build();
        try (TransportService service = buildService("TS_TPC", Version.CURRENT, Settings.EMPTY)) {
            PlainActionFuture<Transport.Connection> future = PlainActionFuture.newFuture();
            DiscoveryNode node = new DiscoveryNode(
                "TS_TPC",
                "TS_TPC",
                service.boundAddress().publishAddress(),
                emptyMap(),
                emptySet(),
                version0
            );