As part of WT-4900, we added the new all_durable timestamp and connection level durable timestamp in favour of the now deprecated all_committed timestamp and connection level commit timestamp. The old all_committed and commit names were aliased to the new timestamps to help server switch over. Now that the change has been completed, we should remove any traces of all_committed and connection level commit.

Note: this ticket is going to only cover the work of removing all_committed timestamp. A follow-on ticket WT-5397 will take care of removing connection-level commit timestamp, as that part of work has some impact to MongoDB.