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.

tests/files/packet_ubuntu22-calico-all-in-one.yml

@@ -6,6 +6,8 @@ vm_memory: 1600
 
 # Kubespray settings
 auto_renew_certificates: true
+kubeadm_ignore_preflight_errors:
+  - Mem
 
 # Currently ipvs not available on KVM: https://packages.ubuntu.com/search?suite=focal&arch=amd64&mode=exactfilename&searchon=contents&keywords=ip_vs_sh.ko
 kube_proxy_mode: iptables

tests/files/packet_ubuntu24-calico-etcd-datastore.yml

@@ -6,6 +6,8 @@ vm_memory: 1600
 
 # Kubespray settings
 auto_renew_certificates: true
+kubeadm_ignore_preflight_errors:
+  - Mem
 
 # Currently ipvs not available on KVM: https://packages.ubuntu.com/search?suite=noble&arch=amd64&mode=exactfilename&searchon=contents&keywords=ip_vs_sh.ko
 kube_proxy_mode: iptables