Automatic merge from submit-queue (batch tested with PRs 65290, 65326, 65289, 65334, 64860). 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>.
Add a GPUClusterDowngrade test.
**What this PR does / why we need it**:
We actually need a separate GPUClusterDowngrade test to run gpu downgrade tests defined in e.g.,
https://k8s-testgrid.appspot.com/wg-resource-management#gce-1.11-1.10-gpu-master-downgrade
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #
**Special notes for your reviewer**:
**Release note**:
```release-note
```
449908488f