Obtain the prefix name of thread pool in thread pool monitoring

- [ ] 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

EN: Obtain the prefix name of thread pool in thread pool monitoring

中文：IO线程池监控中线程池的名字目前未获取到，需要在线程池监控中将真实的线程池前缀名字拿到

Start by locating the IO thread pool monitoring implementation and the code that creates or names its thread pool. Trace how the pool name reaches monitoring, then verify that monitoring exposes the real thread-pool prefix name rather than leaving it unavailable.

Written by the indexing model from the issue text.