Observability task: sorting out other indicators（可观测性任务其他指标项梳理）

- [x] 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: Of course, the core functions of dubbo are not just the providers and consumers listed above, and the three major centers. Dubbo also has powerful functions such as traffic management and service management. It can be perfected.

中文：当然dubbo的核心功能并不是仅仅只有前面列举的提供者和消费者，和三大中心，dubbo还有强大的流量治理，服务治理等功如果你能挖掘出具有实际需求场景的位置需要埋点的话可以将其完善。

Start by reviewing Dubbo's existing observability coverage for traffic management and service governance, then identify concrete user scenarios that need additional indicators. The issue does not name files, entry points, or tests, so first map the relevant instrumentation areas and clarify the expected metrics. Done should be defined as an agreed list of indicators and implementation scope.

Written by the indexing model from the issue text.