In T406515, we added a user_central_id column to mediawiki_content_* tables.
However, this column needs to be backfilled.
In this task we should take care of that, and make sure this is reflected on all the content tables:
- Backfill user_central_id on wmf_content.mediawiki_content_history_v1
- Backfill user_central_id on wmf_content.mediawiki_content_current_v1
- Backfill user_central_id on wmf_content.mediawiki_revision_history_v1