This deprecation started in T279886. I'm creating this dedicated task to track the migration (for core/WMF), and removal. Once it is closed it could also continue to be communication venue for any later fall-out and for reference by patches in other repos.
- Deprecated in 1.37, https://gerrit.wikimedia.org/r/693192, https://gerrit.wikimedia.org/r/699530
- Remove in 1.38?