Automatic merge from submit-queue (batch tested with PRs 40385, 40786, 40999, 41026, 40996)
kubeadm: change os.Remove to os.RemoveAll
**What this PR does / why we need it**: This would not correctly clean out the tmp dir, since os.Remove doesn't recursively remove dirs, which could exist in the tmp dir.
Unit tests are a WIP from #34136
**Special notes for your reviewer**: /cc @luxas @pires
**Release note**:
```release-note
NONE
```
751cbc9b0c