Depending on the value returned from QueueingHintFn, the scheduling queue changes how it queues each Pod:
  - if more than one QueueingHintFn returns QueueImmediately, it queues Pod to activeQ.
  - If no QueueingHintFn returns QueueImmediately and more than one plugin returns QueueAfterBackoff, it queues Pod to backoffQ if Pod is backing off, or to activeQ if Pod's backoff has already finished.

- Add "reason" field to image_garbage_collected_total metric, so admins can differentiate images that were collected for reason "age" vs "space" ([#123345](https://github.com/kubernetes/kubernetes/pull/123345), [@haircommander](https://github.com/haircommander)) [SIG Node]