Support metrics grouped by scope labelValue in MAL, no need global same labelValue as before. (#6495)

Add telemetry data about metrics in, metrics scraping and trace in metrics to zipkin receiver. (#6516)

* CDS: Support config `agent.span_limit_per_segment`

* fix missing logical.

* fix ci

* polish
Co-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>

Resolves #6481

Co-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>
Co-authored-by: NZhenxu Ke <kezhenxu94@apache.org>

* Add `sum` function in meter system

* Fix minor potential bug and reformat some codes

* Fix a bug

* Use Set to hold the {aggregate,scope} labels as same labels maybe added by multiple aggregation functions

* Separate downsampling function and revert unnecessary codes