Automatic merge from submit-queue (batch tested with PRs 63787, 62003). 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: Use the API machinery for marshalling
**What this PR does / why we need it**:
Similar to https://github.com/kubernetes/kubernetes/pull/63723, we should not use a generic `yaml`
package for marshalling, but use the API machinery we have already in place. This now correctly includes `apiVersion` and `kind` when printing the configuration in the upgrade procedure.
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Part of https://github.com/kubernetes/community/pull/2131
**Special notes for your reviewer**:
**Release note**:
```release-note
NONE
```
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