Refactor `AbstractSimpleTransportTestCase` and `MockTransportService` to not use `Version.transportVersion` 
test/framework/src/main/java/org/elasticsearch/transport/AbstractSimpleTransportTestCase.java
}
                        }
                    );
                } else {
                    logger.debug("send response for {}", request.info);
                    channel.sendResponse(new TestResponse("Response for: " + request.info));
                }
            }
        }
        serviceB.registerRequestHandler(
            "internal:action1",
            randomFrom(ThreadPool.Names.SAME, ThreadPool.Names.GENERIC),
            TestRequest::new,
            new TestRequestHandler(serviceB)
        );
        serviceC.registerRequestHandler(
            "internal:action1",
            randomFrom(ThreadPool.Names.SAME, ThreadPool.Names.GENERIC),
            TestRequest::new,
            new TestRequestHandler(serviceC)
        );
        serviceA.registerRequestHandler(
            "internal:action1",
            randomFrom(ThreadPool.Names.SAME, ThreadPool.Names.GENERIC),
            TestRequest::new,
            new TestRequestHandler(serviceA)
        );
        int iters = randomIntBetween(30, 60);
        CountDownLatch allRequestsDone = new CountDownLatch(iters);
        class TestResponseHandler implements TransportResponseHandler<TestResponse> {