Sub-Issue of #1976158: [meta] Rename entity storage/list/form/render "controllers".
Rename Drupal\content_translation\ContentTranslationController (not the other one in the Controller namespace!) to ContentTranslationHandler.
Then to do the same for all subclasses of this for Node, Term and so on.
This class is referenced in the entity annotations, so make sure to do a text search for the class name so that you find those references as well.