Automatic merge from submit-queue (batch tested with PRs 63453, 64592, 64482, 64618, 64661). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Revert "Remove rescheduler and corresponding tests from master"
Reverts kubernetes/kubernetes#64364
After discussing with @bsalamat on how DS controllers(ref: https://github.com/kubernetes/kubernetes/pull/63223#discussion_r192277527) cannot create pods if the cluster is at capacity and they have to rely on rescheduler for making some space, we thought it is better to
- Bring rescheduler back.
- Make rescheduler priority aware.
- If cluster is full and if **only** DS controller is not able to create pods, let rescheduler be run and let it evict some pods which have less priority.
- The DS controller pods will be scheduled now.
So, I am reverting this PR now. Step 2, 3 above are going to be in rescheduler.
/cc @bsalamat @aveshagarwal @k82cn
Please let me know your thoughts on this.
```release-note
Revert #64364 to resurrect rescheduler. More info https://github.com/kubernetes/kubernetes/issues/64725 :)
```
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