Automatic merge from submit-queue. 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>.

Move of unreachable taint key out of alpha

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

Move of unreachable taint key out of alpha, which already happened in community doc.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #54198

**Special notes for your reviewer**:
Please see #54198 for the context of this inconsistency.

**Release note**:

```release-note
Move unreachable taint key out of alpha. 
Please note the existing pods with the alpha toleration should be updated by user himself to tolerate the GA taint.
```