Automatic merge from submit-queue (batch tested with PRs 56997, 57008, 56984, 56975, 56955). 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>.

Remove unused ScrubDNS interface from cloudprovider

**What this PR does / why we need it**:

DNS scrubber from kubelet has been removed in #36785 and cloudprovider's `ScrubDNS()` interface is not used anywhere.

**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 #56953.

**Special notes for your reviewer**:

**Release note**:

```release-note
Remove ScrubDNS interface from cloudprovider.
```