Context: For multiple Contributors work streams, we need to calculate user edit counts across all wikis. We are using the wmf_contributors.editor_month table. However, there is no central ID field; so we're using user_name. As a result, for users who have changed their username, it doesn't count the edits before their name change. Now that user_central_id has been added to mediawiki_history (see T365648#11714962), can we add that field to the editor_month table?

Request: Add user_central_id field to the wmf_contributors.editor_month table.