Externalize ".. of .. checklist items completed" to make it translatable
<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=386495) </details> <!--IssueSummary end--> The following discussion from !107233 should be addressed: - [ ] @mrincon started a [discussion](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/107233#note_1217665643): > ... > > Also, this string will fail in other languages, I am not sure if there may be an issue for this already?
issue