Reason: Obsolete (requires LQT), and has security flaws. Only one wiki using it in WikiApiary, and that wiki is on 1.16.x, so it wouldn't even affect them anyways.
- Archive documentation on mediawiki.org (https://www.mediawiki.org/wiki/Extension:Reflect).
- 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 an ARCHIVED file.
- Remove from https://doc.wikimedia.org/cover-extensions/ if present (requires Continuous-Integration-Infrastructure shell user to delete directly from the server)
- Archive the extension's diffusion repository: https://phabricator.wikimedia.org/diffusion/EREF/
- Mark the repository read-only in Gerrit: https://gerrit.wikimedia.org/g/mediawiki/extensions/Reflect
- Delete the GitHub mirror: https://github.com/wikimedia/mediawiki-extensions-Reflect