Resolve "Labeling system notes downcase labels"

## What does this MR do?
This MR fixes issues of label gets lowercase in system note as describe in #24737

## Are there points in the code the reviewer needs to double check?
NR
## Why was this MR needed?
This MR fixes the regression of becoming labels and its description and title lowercase in system note
  
## Screenshots (if relevant)
**Before:**
![before](/uploads/ac99fd5d1219ee3b4b7c699319267087/before.png)

**After:** 
![after](/uploads/d1b6413c857d18f122252f421ac498b0/after.png)

## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?


Closes #24737 
Closes #24751

See merge request !7636