Automatic merge from submit-queue (batch tested with PRs 55380, 55399, 55377, 55055). 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: Make swap check as an error
**What this PR does / why we need it**:
Based on amount of support issues where warning about enabled
swap not noticed or ignored, it will be better to make this
check as an error.
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
**Special notes for your reviewer**:
cc @luxas
attention @jpbetz : this change planned to be also cherrypicked to 1.8 branch.
/area kubeadm
/sig cluster-lifecycle
**Release note**:
```release-note
kubeadm now produces error during preflight checks if swap is enabled. Users, who can setup kubelet to run in unsupported environment with enabled swap, will be able to skip that preflight check.
```
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