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>.

bazel: kubelet deb package postinstall step

**What this PR does / why we need it**:
Presently bazel build .deb (kubelet.deb specifically) does not auto-restart after installation. Adding a postinst control file fixes this.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
kubernetes/kubeadm#944
**Special notes for your reviewer**:

@chuckha  

```release-note
bazel deb package bugfix: The kubeadm deb package now reloads the kubelet after installation
```