Resolve commit comments displayed on a merge request

- Added missing i18n strings
- Added changelog entry
- Fixed lint errors

changelogs/unreleased/53950-commit-comments-displayed-on-a-merge-request.yml

+---
+title: Display "commented" only for commit discussions on merge requests
+merge_request: 24427
+author:
+type: changed

locale/gitlab.pot

@@ -4294,6 +4294,9 @@ msgstr ""
 msgid "MergeRequests|View replaced file @ %{commitId}"
 msgstr ""
 
+msgid "MergeRequests|commented on commit "
+msgstr ""
+
 msgid "MergeRequests|started a discussion"
 msgstr ""