In UpdateOne, after an update is complete in UpdateOne, we reset the collection stage to open a new cursor. This opens up a new WT transaction but this transaction is never user for anything. Instead, we simply time opening and closing the transaction. In the case where we know we are in an UpdateOne, we should simply skip this step.

I have not quantified this change in a standalone patch.

POC: https://github.com/10gen/mongo/commit/a6e7304dc082ef858e83b9fb924376780bea365c