Push status updates as soon as readiness state changes for containers,
rather than waiting for the sync loop to update the status. In
particular, this should help new containers to come online faster.
Additionally, consolidates prober test helpers into a single file.
- status.Manager always deals with the local (static) pod, but gets the
mirror pod when syncing
- This lets components like the probe workers ignore mirror pods
- Fix deadlock when syncing deleted pods with full update channel
- Prevent sending stale updates to API server
- Don't delete cached status when sync fails (causes problems for prober)
This refactor is in preparation for moving more state handling to the
status manager. It will become the canonical cache for the latest
information on running containers and probe status, as part of the
prober refactoring.
