Set certs and files with kubeadm token to mode 0640 (#5325)

roles/kubernetes/master/tasks/kubeadm-certificate.yml

roles/kubernetes/master/tasks/kubeadm-fix-apiserver.yml

roles/kubernetes/master/tasks/kubeadm-migrate-certs.yml

...ubernetes/master/tasks/kubeadm-secondary-experimental.yml

roles/kubernetes/master/tasks/kubeadm-secondary-legacy.yml

roles/kubernetes/master/tasks/kubeadm-version.yml