Refactor `AbstractSimpleTransportTestCase` and `MockTransportService` to not use `Version.transportVersion` 
x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/transport/netty4/SimpleSecurityNetty4ServerTransportTests.java
final Settings qcSettings1 = Settings.builder().build();
            try (MockTransportService qcService = buildService("QC", Version.CURRENT, qcSettings1)) {
                final ConnectTransportException e = expectThrows(
                    ConnectTransportException.class,
                    () -> openConnection(qcService, node, connectionProfile)
                );
                assertThat(
                    e.getRootCause().getMessage(),
                    anyOf(containsString("unable to find valid certification path"), containsString("Unable to find certificate chain"))
                );
            }
            
            final Settings qcSettings2 = Settings.builder()
                .put("xpack.security.remote_cluster_client.ssl.verification_mode", "none")
                .build();
            try (
                MockTransportService qcService = buildService("QC", Version.CURRENT, qcSettings2);
                Transport.Connection connection = openConnection(qcService, node, connectionProfile)
            ) {
                assertThat(connection, instanceOf(StubbableTransport.WrappedConnection.class));
                Transport.Connection conn = ((StubbableTransport.WrappedConnection) connection).getConnection();
                assertThat(conn, instanceOf(TcpTransport.NodeChannels.class));
                TcpTransport.NodeChannels nodeChannels = (TcpTransport.NodeChannels) conn;
                for (TcpChannel channel : nodeChannels.getChannels()) {
                    assertFalse(channel.isServerChannel());
                    assertThat(channel.getProfile(), equalTo("_remote_cluster"));
                    final SSLEngine sslEngine = SSLEngineUtils.getSSLEngine(channel);
                    assertThat(sslEngine.getUseClientMode(), is(true));
                }
                final TcpChannel acceptedChannel = getAcceptedChannel(originalTransport, connection);