Fix review requests becoming private after discard, reopen, close.

When marking a review request as discarded and then reopening, we force
the user to complete a draft and publish it, since the typical reason
you discard is that you've thrown away the review request, and reopening
means you're starting over on some aspect of it.

Sometimes, the discard is accidental, and a user will fix this by just
closing it again as submitted. Unfortunately, the act of reopening marks
it as not public, and that state remains when marking as submitted.

We now mark a review request as public if it's closed as submitted.

Fixes bug #3103