### 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
"TEST",
                new TransportAddress(socket.getInetAddress(), socket.getLocalPort()),
                emptyMap(),
                emptySet(),
                version0
            );
            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 (TransportService service = buildService("TS_TPC", Version.CURRENT, null, Settings.EMPTY, true, false)) {
                IOUtils.close(openConnection(service, first, builder.build()));
                builder.setConnectTimeout(TimeValue.timeValueMillis(1));
                final ConnectionProfile profile = builder.build();
                
                long startTime = System.nanoTime();
                ConnectTransportException ex = expectThrows(
                    ConnectTransportException.class,
                    () -> openConnection(service, second, profile)
                );
                final long now = System.nanoTime();
                final long timeTaken = TimeValue.nsecToMSec(now - startTime);
                assertTrue(
                    "test didn't timeout quick enough, time taken: [" + timeTaken + "]",