Our logs are awful and this commit attempts to fix some issues with
* Make sure we always indicate why some readiness or liveness probe
* Suppress INFO logs from werkzeug (so that we don't see every probe
call on INFO level).
* Remove logging of successful probe checks.
* Make watcher restart logs less scary and include more cases.
* Add backoff to watcher restarts so that we don't spam logs when K8s
API is briefly unavailable.
* Add warnings for low quotas.
* Suppress some long logs on K8s healthz failures - we don't need full
message from K8s printed twice.
I also refactored CNI and controller health probes servers to make sure
they're not duplicating code.