Automatic merge from submit-queue (batch tested with PRs 63735, 62807). 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: Update comments and UT to remove /66 restriction
**What this PR does / why we need it**:
The comments in cmd/kubeadm/app/phases/controlplane/manifests.go mention the
IPv6 /66 restriction, and the UT also refers to this.
This restriction was removed in PR#60089
This removes those comments and updates the UT
**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#62806
**Special notes for your reviewer**:
**Release note**:
```release-note-none
```
f5a91f4173