Do not wait so long in kcidb_load_queue

Right now the kcidb_load_queue Cloud Function waits for about 30 seconds for new messages to arrive via the message queue. This was likely done because the queue wouldn't give up all messages at once, increasing submission latency. Check if that's really true and try to reduce the wait time, so we're not billed so much for the run time once billing starts.

Start by locating the kcidb_load_queue Cloud Function and the message-queue handling it uses. Check whether the queue releases messages incrementally, measure the effect of reducing the roughly 30-second wait on submission latency and completeness, and confirm that the function finishes sooner without leaving messages unprocessed.

Written by the indexing model from the issue text.