feat: monitor etcd

[uhthomas]

It looks like etcd does not run in-cluster with Talos, and therefore is not easy to monitor.

[uhthomas]

name: "vm-victoria-metrics-k8s-stack-kube-etcd"
spec: {
	selector: matchLabels: {
		app:                          "vm-victoria-metrics-k8s-stack-kube-etcd"
		"app.kubernetes.io/instance": "vm"
	}
	namespaceSelector: matchNames: [
		"kube-system",
	]
	endpoints: [{
		bearerTokenFile: "/var/run/secrets/kubernetes.io/serviceaccount/token"
		port:            "http-metrics"
		scheme:          "https"
		tlsConfig: caFile: "/var/run/secrets/kubernetes.io/serviceaccount/ca.crt"
	}]
	jobLabel: "jobLabel"
}