Arena client API: Change locks to have no wait time
When searching for the next match to select, there's no need to wait for a lock on any specific queued match/bot - just move on to the next possible match. Current I believe the API will wait for locks to be acquired, meaning many ACs requesting matches probably lock down the system.
Once implemented, write a test like so:
ascertain which match should come next
lock said match in some way to make the request skip that match due to the lock and return the next match
request match - sanity check it's the expected one
unlock the locked match
request match - sanity check it's the expected one```