Reason: https://gerrit.wikimedia.org/r/#/admin/projects/mediawiki/extensions/AccountAudit is marked as Read Only but there are some leftovers which I'd like it cleaned.
- Archive documentation on mediawiki.org.
- Remove from mediawiki/extensions (along with in .gitmodules)
- 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 the extension's diffusion repository: rEAAU
- Mark the repository read-only in Gerrit.
- Delete the GitHub mirror: https://github.com/wikimedia/mediawiki-extensions-AccountAudit