## Summary
Adds a `RUN_ENGINE_DEQUEUE_DISABLED_WORKER_QUEUES` setting that refuses
worker dequeue requests for the listed worker queues (or base regions),
so their runs stay queued instead of being handed to workers that can't
run them. Blocked dequeues are counted via a
`run_engine.dequeue.blocked` OTel counter (labeled by `worker_queue` and
`region`).
Eric Allam