Dropping the config.system.sessions collection is not permitted via a mongos command, it is explicitly blocked.

However, to support TSEs/COEs in resolving known bugs for customers, we maintain internal documentation describing a manual workaround: connect to each shard individually, drop the collection locally, then delete the corresponding entries from config.collections and config.chunks so the collection can be safely re-created.

With the introduction of authoritative shards and shard-local catalog collections, this procedure is now incomplete. We need to:

1. Locate and update the existing playbook (KB000021629) to also include dropping the corresponding documents from the shard-local catalog collections: config.shard.catalog.collections and config.shard.catalog.chunks.
2. Update the server-side test hook that reproduces this playbook scenario — drop_sessions_collection.py — so it stays consistent with the corrected procedure.