Once T366546: Remove wgCheckUserEventTablesMigrationStage and related migration code is complete, and therefore the migration stage is set to read and write new only permanently, we can run the script to remove entries from cu_changes that are only for use when reading old that was added in T341830: Create maintenance script to delete entries only for read old on WMF wikis.
Acceptance criteria
- Run deleteReadOldRowsInCuChanges.php on testwiki
- Run deleteReadOldRowsInCuChanges.php on group0 wikis
- Run deleteReadOldRowsInCuChanges.php on group1 wikis
- Run deleteReadOldRowsInCuChanges.php on group2 wikis