**Reason**: Code moved into #timedmediahandler in {T164037}.
- [x] Stop branching for Wikimedia production: https://gerrit.wikimedia.org/r/c/mediawiki/tools/release/+/441523
- [x] Remove from Wikimedia production: https://gerrit.wikimedia.org/r/c/operations/mediawiki-config/+/441521/
- [x] Archive documentation on `mediawiki.org` (https://www.mediawiki.org/wiki/Extension:MwEmbedSupport)
- [x] Remove tests in `integration/config`: https://gerrit.wikimedia.org/r/#/c/integration/config/+/443006
- [x] Remove from `translatewiki`: https://gerrit.wikimedia.org/r/#/c/translatewiki/+/444937
- [x] Remove from `mediawiki/extensions` (along with in `.gitmodules`)
Todo later (not doing this for now):
- [ ] Empty repository and add an `ARCHIVED` file
- [ ] Archive the extension's Diffusion repository
- [ ] Mark the repository read-only in Gerrit
- [ ] Delete the GitHub mirror
- [ ] Archive Phabricator project #MwEmbedSupport for associated extension/skin and edit its description for associated extension/skin with a link to this ticket