Following up on SERVER-80862, which asks to have the config.transactions table be created as a clustered collection, we need to address the upgrade concern of existing clusters gaining the performance benefit of clustered config.transactions as well as the downgrade concern of clusters expecting nonclustered config.transactions, but receiving clustered config.transactions.

Service Arch has proposed that commands be introduced that convert the config.transactions collection between the nonclustered and clustered formats, and that those commands be integrated into Atlas' upgrade/downgrade procedures (originally proposed in SERVER-80862 by max.hirschhorn@mongodb.com).