Optimize queries when publishing or discarding review drafts.
Our Review publishing and discarding code was very inefficient. During

publish, we'd do 3 queries (one for every comment type), then a save on

each instance of a comment, which would end up doing an update of a

ReviewRequest per-comment. During delete, we'd do the 3 queries plus a

delete on each instance.
We now do 3 queries for publishing comments, and 3 for deleting.

Unit tests pass.
Published and discarded drafts without problems.