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>.
Fixed TearDown of NFS with root squash.
NFS plugin should not use `IsLikelyNotMountPoint()`, as it uses `lstat()` / `stat()` to determine if the NFS volume is still mounted - NFS server may use root_squash and kubelet may not be allowed to do `lstat()` / `stat()` there.
It must use slower `IsNotMountPoint()` instead, including in `TearDown()` function.
**Release note**:
```release-note
NONE
```
/assign @gnufied @rootfs
74f2305c4f