Automatic merge from submit-queue (batch tested with PRs 58899, 58980). 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>.

Fix setting qps in density test.

Current QPS setting code doesn't work. All the density tests with higher QPS are failing. https://k8s-testgrid.appspot.com/sig-node-kubelet#kubelet-benchmark-gce-e2e

We should use existing helper function `tempSetCurrentKubeletConfig` to set QPS.

@kubernetes/sig-node-bugs @mtaufen 

**Release note**:

```release-note
none
```