**Reason**: See T195127. (self-assigning this) This task should not be done until the code is merged into SocialProfile.
- [x] Archive documentation on `mediawiki.org`: https://www.mediawiki.org/wiki/Extension:RandomFeaturedUser
- [ ] Remove from `mediawiki/extensions`
- [ ] Remove tests in `integration/config`
- [ ] Remove from `translatewiki`: `groups/MediaWiki/mediawiki-extensions.txt`
- [x] Remove manifest/other references from `mediawiki/vagrant` if they exist (not relevant)
- [x] Empty repository and add an `ARCHIVED` file.
- [x] Archive Phabricator project: #randomfeatureduser
- [x] Edit Phabricator project description of #randomfeatureduser with a link to this ticket
- [ ] Archive the extension's diffusion repository: https://phabricator.wikimedia.org/diffusion/ERFU/
- [x] Mark the repository read-only in Gerrit: https://gerrit.wikimedia.org/r/#/admin/projects/mediawiki/extensions/RandomFeaturedUser
- [ ] Delete the GitHub mirror: https://github.com/wikimedia/mediawiki-extensions-RandomFeaturedUser