Stricter kubeadm validation (config and runtime checks) (#11710)

* 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.

roles/kubernetes/kubeadm/tasks/kubeadm_etcd_node.yml

@@ -9,6 +9,7 @@
     src: "kubeadm-client.conf.j2"
     dest: "{{ kube_config_dir }}/kubeadm-cert-controlplane.conf"
     mode: "0640"
+    validate: "{{ bin_dir }}/kubeadm config validate --config %s"
   vars:
     kubeadm_cert_controlplane: true