Fix remaining offenses for cop `Cop/StaticTranslationDefinition` related to diff_viewer
The following discussion from !100168 should be addressed:
- [ ] @splattael started a [discussion](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/100168#note_1131350961):
> See https://gitlab.com/gitlab-org/gitlab/-/blob/0ff93efa9e72f85ed72112e186ec79dbe0face7d/app/models/diff_viewer/image.rb#L12
>
> It's a good idea to fix this a follow-up :thumbsup: because it requires more work and more :eyes: from domain experts.
issue