Count hsdir requests against maxcircuitspending
In #13837 (moved), we split off hsdir purposes from general. In the process, it means that we stopped counting hsdir circuits towards the global pending rate limit in count_pending_general_client_circuits(). That function was already trying to avoid counting hs circuits, but since nothing else globally limits the number of pending hs circuits, we probably should keep rate limiting hsdirs there, too.