Automatic merge from submit-queue (batch tested with PRs 46787, 46876, 46621, 46907, 46819)

kubeadm: Only create bootstrap configmap if not exists.

**What this PR does / why we need it**:
The fact that this method was not idempotent was breaking kubeadm upgrades.

https://github.com/kubernetes/kubeadm/issues/278

**Release note**:

```release-note
NONE
```