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>.

Remove bootstrap kubelet config on reset

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

Remove /etc/kubernetes/bootstrap-kubelet.conf when running 'kubeadm reset'
to ensure it will not be reused when joining the cluster next time.

**Release note**:
```release-note
NONE
```