[enhancement] use BRPOPLPUSH instead of BLPOP for notifying waiting jobs

Currently we have a special list wait:added used for notifying that new jobs have arrived to the queue. This works well but can be done better. If we use BRPOPLPUSH instead but using the same source and destination, we can have only one list and get rid of wait:added, this simplifies code but also has another advantage, we can call moveToActive directly to avoid an extra call to BLPOP, for instance if the queue has not drained we can just keep moving jobs to the active list faster.