**Reason**:
i18n error messages have been broken for three years ( T199033 ). It barely got any code update and wikiapiary only find a single wiki using it.
- [x] Archive documentation on `mediawiki.org` https://www.mediawiki.org/wiki/Extension:Transliterator
- [ ] Remove from `mediawiki/extensions` ( along with in `.gitmodules`)
- [x] Remove tests in `integration/config` ( `zuul/layout.yaml` )
- [ ] Remove from `translatewiki` ( `groups/MediaWiki/mediawiki-extensions.txt` )
- [ ] Remove manifest/other references from `mediawiki/vagrant` if they exist
- [ ] Empty repository and add a OBSOLETE file.
- [ ] Archive Phabricator project #mediawiki-extensions-transliterator for associated extension/skin
- [ ] Edit Phabricator project #mediawiki-extensions-transliterator description for associated extension/skin with a link to this ticket
- [ ] Archive the extension's diffusion repository: ETRX
- [ ] Mark the repository read-only in Gerrit: https://gerrit.wikimedia.org/r/#/admin/projects/mediawiki/extensions/Transliterator
- [ ] Delete the GitHub mirror: https://github.com/wikimedia/mediawiki-extensions-Transliterator