* 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

Co-authored-by: NMargaux Cabrera <margaux.cabrera@skulibrary.com>
Co-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>

Happy Chinese New Year !!

Add some defensive codes for NPE and bump up Kubernetes client version to expose exception stack trace (#6327)

* Update frontend-maven-plugin to 1.11.0, for Download node x64 binary on Apple Silicon.

* Update CHANGES.md

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