Under cache pressure, WT might want to rollback a read-only transaction. For example, if that transaction is pinning the oldest timetamp and therefore is potentially keeping extra data in the cache.

WT does this in standalone builds, but not when it is part of MongoDB, largely because the upper layers or MongoDB aren't expecting to get a rollback error on transaction that hasn't dirtied any data. (See SERVER-44870)

This ticket is to enable the rollback of read-only transactions on non-standalone builds, if and when the server can handle that.