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

otc/observability.buildth.ing/stacks/observability/victoria-k8s-stack/values.yaml

@@ -711,10 +711,8 @@ vmagent:
     port: "8429"
     selectAllByDefault: true
     scrapeInterval: 20s
-    externalLabels: {}
-      # For multi-cluster setups it is useful to use "cluster" label to identify the metrics source.
-      # For example:
-      # cluster: cluster-name
+    externalLabels:
+      cluster: observability
     extraArgs:
       promscrape.streamParse: "true"
       # Do not store original labels in vmagent's memory by default. This reduces the amount of memory used by vmagent
@@ -921,6 +919,11 @@ prometheus-node-exporter:
             - action: drop
               source_labels: [mountpoint]
               regex: "/var/lib/kubelet/pods.+"
+            - action: replace
+              source_labels: [__name__, instance]
+              regex: "node_uname_info;([^:]+):.+"
+              target_label: nodename
+              replacement: "$1"
 # -- kube-state-metrics dependency chart configuration. For possible values check [here](https://github.com/prometheus-community/helm-charts/blob/main/charts/kube-state-metrics/values.yaml)
 kube-state-metrics:
   enabled: true