Automatic merge from submit-queue (batch tested with PRs 41104, 41245, 40722, 41439, 41502)
Bump the minimum kubeadm control plane version to v1.6.0-alpha.2
**What this PR does / why we need it**:
There went in quite a lot of useful features into v1.6.0-alpha.2 that kubeadm will use.
This bump the minimum limit so we can depend on those features.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
**Special notes for your reviewer**:
**Release note**:
```release-note
NONE
```
@mikedanese @errordeveloper @pires @dmmcquay @dgoodwin
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