Automatic merge from submit-queue (batch tested with PRs 57366, 57779). 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 command waitfordetach from flex volume driver
**What this PR does / why we need it**:
Clean unused code.
**Special notes for your reviewer**:
See #35629
Original PR is https://github.com/kubernetes/kubernetes/pull/50754 , the PR's repo has bean deleted，so I create a new PR and merge upstream for test.
**Release note**:
```release-note
NONE
```
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