* kubeadm: do not ignore preflight errors blindly
The "ignoring all errors" seems to date back to the inception of the
kubeadm support (it was --skip-preflight-check before).
This can mask real errors and prevent users from seeing them.
Do not ignore any errors by default and make the set of ignored errors
configurable.
* download/kubeadm: remove redundant task
The mode is already set by the previous `copy` task.
* Validate kubeadm configs
This should help to fail early when we have invalid kubeadm configs (from
a kubespray bug or a misconfiguration).
* kubeadm-upgrade: remove unnecessary bool cast
* Convert kubeadm join discovery timeout to v1beta4 config
* CI: Ignore kubeadm:Mem errors on some setup.
68718dcb6f