客户端优化，收到DISCONNECT消息时断开代理隧道连接

neutrino-proxy-client/src/main/java/org/dromara/neutrinoproxy/client/handler/ProxyMessageDisconnectHandler.java

@@ -29,6 +29,7 @@ public class ProxyMessageDisconnectHandler implements ProxyMessageHandler {
 			ProxyUtil.returnProxyChanel(ctx.channel());
 			realServerChannel.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
 		}
+		ctx.close();
 	}
 
 	@Override