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>.
kubeadm: Don't downgrade etcd on cluster downgrade
**What this PR does / why we need it**:
- Don't try downgrade etcd on k8s downgrade -- that doesn't work
- Mark self-hosting as alpha as discussed in the SIG
- Don't print the beta warning as it confuses users
- Slightly make the wording around upgrade/downgrade clearer
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #
**Special notes for your reviewer**:
**Release note**:
```release-note
NONE
```
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