fix(observability): enable ArgoCD/CoreDNS scraping, add cluster label, fix node dashboard

otc/observability.buildth.ing/stacks/observability/victoria-k8s-stack/manifests/argocd-scrape.yaml

@@ -0,0 +1,13 @@
+apiVersion: operator.victoriametrics.com/v1beta1
+kind: VMServiceScrape
+metadata:
+  name: argocd
+spec:
+  namespaceSelector:
+    matchNames:
+      - argocd
+  selector:
+    matchLabels:
+      app.kubernetes.io/part-of: argocd
+  endpoints:
+    - port: metrics

otc/observability.buildth.ing/stacks/observability/victoria-k8s-stack/manifests/coredns-scrape.yaml

@@ -0,0 +1,14 @@
+apiVersion: operator.victoriametrics.com/v1beta1
+kind: VMPodScrape
+metadata:
+  name: coredns
+spec:
+  namespaceSelector:
+    matchNames:
+      - kube-system
+  selector:
+    matchLabels:
+      k8s-app: coredns
+  podMetricsEndpoints:
+    - targetPort: 9153
+      path: /metrics