**Reason**:
The installation has been failing since MediaWiki 1.23 which added the `page_links_updated` column in the database. 1.23 got released in June 2014. The extension is not installable indicating that nobody tried installing it.
Wikiapiary shows zero installation https://wikiapiary.com/wiki/Extension:InterwikiIntegration
- [X] Archive documentation on `mediawiki.org` ( https://www.mediawiki.org/wiki/Extension:InterwikiIntegration )
- [ ] 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` )
- [x] Empty repository and add a OBSOLETE file.
- [x] Archive the extension's diffusion repository: ( https://phabricator.wikimedia.org/diffusion/EIWI/ )
- [x] Mark the repository read-only in Gerrit: ( https://gerrit.wikimedia.org/r/#/admin/projects/mediawiki/extensions/InterwikiIntegration )
- [ ] Delete the GitHub mirror: https://github.com/wikimedia/mediawiki-extensions-InterwikiIntegration