fix(monitoring): disable control-plane alerts and scrapes on k0s

k0s runs kube-controller-manager, kube-scheduler and etcd inside its own
process rather than as pods, so the chart's Services never get endpoints
and the targets stay permanently absent. Drop the matching ServiceMonitors
and their Down/HighCommitDurations rules; kube-proxy and kubelet do get
endpoints on k0s and stay enabled.

prometheus-stack/k8s/grafana-values.yaml

@@ -69,3 +69,18 @@ alertmanager:
 defaultRules:
   disabled:
     CPUThrottlingHigh: true
+    KubeControllerManagerDown: true
+    KubeSchedulerDown: true
+    KubeEtcdDown: true
+    KubeEtcdHighCommitDurations: true
+
+# k0s runs controller-manager/scheduler/etcd internally, not as pods with
+# component=kube-controller-manager/kube-scheduler/k8s-app=kube-etcd labels.
+# Their Services get no endpoints, so the targets are permanently down.
+# kube-proxy and kubelet have endpoints on k0s, keep them enabled.
+kubeControllerManager:
+  enabled: false
+kubeScheduler:
+  enabled: false
+kubeEtcd:
+  enabled: false