Automatic merge from submit-queue

kubeadm: Make kube-proxy RollingUpgradeable

**What this PR does / why we need it**:
Sets the right updateStrategy for kube-proxy.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #

Fixes: https://github.com/kubernetes/kubeadm/issues/319

**Special notes for your reviewer**:

**Release note**:

```release-note
NONE
```
@pipejakob @timothysc @kubernetes/sig-cluster-lifecycle-pr-reviews