[Observable tasks] add netty related indicators

- [ ] I have searched the [issues](https://github.com/apache/dubbo/issues) of this repository and believe that this is not a duplicate.

## Describe the proposal
Observable tasks add netty related indicators
At present, the latest version of micrometer has added Netty related monitoring indicators. The Java version of Dubbo uses the Netty framework at the bottom, which can be explored and developed to improve monitoring indicators.

可观测任务增加netty相关指标
目前最新版本的micrometer新增了netty相关的监控指标，Java版本的Dubbo底层使用的是Netty框架，可以尝试调研，兼容开发，来完善监控指标

https://github.com/micrometer-metrics/micrometer/releases/tag/v1.11.0