Refactor `AbstractSimpleTransportTestCase` and `MockTransportService` to not use `Version.transportVersion` 
test/framework/src/main/java/org/elasticsearch/transport/AbstractSimpleTransportTestCase.java
threadPool.executor(ThreadPool.Names.GENERIC).execute(new AbstractRunnable() {
                @Override
                public void onFailure(Exception e) {
                    logger.error("unexpected error", e);
                    sendingErrors.add(e);
                }
                @Override
                protected void doRun() throws Exception {
                    go.await();
                    for (int iter = 0; iter < 10; iter++) {
                        PlainActionFuture<TestResponse> listener = new PlainActionFuture<>();
                        final String info = sender + "_" + iter;
                        final DiscoveryNode node = nodeB; 
                        try {
                            serviceA.sendRequest(
                                node,
                                "internal:test",
                                new TestRequest(info),
                                new ActionListenerResponseHandler<>(listener, TestResponse::new)
                            );
                            try {
                                listener.actionGet();
                            } catch (ConnectTransportException e) {
                                
                            } catch (Exception e) {
                                logger.error(() -> format("caught exception while sending to node %s", node), e);
                                sendingErrors.add(e);
                            }
                        } catch (NodeNotConnectedException ex) {