When the migration of database preferences has occurred in T299104 we can remove all code relating to skin versioning to complete the technical goal.
- All code relating to the old preference is removed e.g. includes/HTMLForm/Fields/HTMLLegacySkinVersionField.php
- Make SkinVersion an abstract class and make the isLegacy method a simple return false or return true
- Visit /w/index.php/Selenium_category_test?useskin=vector and confirm you get old Vector
- Visit /w/index.php/Selenium_category_test?useskin=vector-2022 and confirm you get new Vector
- In Special:Preferences confirm you can change to legacy Vector
- In Special:Preferences confirm you can change to modern Vector