Automatic merge from submit-queue (batch tested with PRs 53689, 56880, 55856, 59289, 60249). 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>.

Use `sets` instead of `for` statement in "IsValidAuthorizationMode"

**What this PR does / why we need it**:
Use `sets` instead of `for` statement in "IsValidAuthorizationMode", that will make the code more clearly and concisely.

**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
none
```