With the alpha scheduling queue we move pods from unschedulable to
active on certain events without a backoff. As a result we can cause
starvation issues if high priority pods are in the unschedulable queue.
Implement a backoff mechanism for pods being moved to active.
Closes#56721
We are going to use PodBackoff for controlling backoff when adding
unschedulable pods back to the active scheduling queue. In order to do
this more easily, limit the interface for PodBackoff to only this struct
(rather than exposing BackoffEntry) and change the backing expiry
implementation to be queue based.
This moves plugin/pkg/scheduler to pkg/scheduler and
plugin/cmd/kube-scheduler to cmd/kube-scheduler.
Bulk of the work was done with gomvpkg, except for kube-scheduler main
package.
