Automatic merge from submit-queue (batch tested with PRs 65251, 67255, 67224, 67297, 68105). If you want to cherry-pick this change to another branch, please follow the instructions here: https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md.
Promote mount propagation to GA
**What this PR does / why we need it**:
This PR promotes mount propagation to GA.
Website PR: https://github.com/kubernetes/website/pull/9823
**Release note**:
```release-note
Mount propagation has promoted to GA. The `MountPropagation` feature gate is deprecated and will be removed in 1.13.
```
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