fix(kube-system): Run insecure metrics-server

This patch runs the metrics-server without CA validation since kubeadm
doesn't create proper certificates for kubelets by default. Therefore,
until this is fixed, this patch will work around the issue.

References:
https://v1-21.docs.kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-certs/#renew-certificates-with-the-kubernetes-certificates-api