Use recommended instance label for Prometheus/Alertmanager resources

manifests/prometheus-service.yaml

@@ -3,10 +3,10 @@ kind: Service
 metadata:
   labels:
     app.kubernetes.io/component: prometheus
+    app.kubernetes.io/instance: k8s
     app.kubernetes.io/name: prometheus
     app.kubernetes.io/part-of: kube-prometheus
     app.kubernetes.io/version: 2.31.1
-    prometheus: k8s
   name: prometheus-k8s
   namespace: monitoring
 spec:
@@ -19,7 +19,7 @@ spec:
     targetPort: reloader-web
   selector:
     app.kubernetes.io/component: prometheus
+    app.kubernetes.io/instance: k8s
     app.kubernetes.io/name: prometheus
     app.kubernetes.io/part-of: kube-prometheus
-    prometheus: k8s
   sessionAffinity: ClientIP