kube-prometheus: put in kube-system

These manifests should live in kube-system; otherwise the label selector
won't work.

manifests/k8s/self-hosted/kube-controller-manager.yaml

@@ -1,6 +1,7 @@
 apiVersion: v1
 kind: Service
 metadata:
+  namespace: kube-system
   name: kube-controller-manager-prometheus-discovery
   labels:
     k8s-app: kube-controller-manager

manifests/k8s/self-hosted/kube-dns.yaml

@@ -1,6 +1,7 @@
 apiVersion: v1
 kind: Service
 metadata:
+  namespace: kube-system
   name: kube-dns-prometheus-discovery
   labels:
     k8s-app: kube-dns

manifests/k8s/self-hosted/kube-scheduler.yaml

@@ -1,6 +1,7 @@
 apiVersion: v1
 kind: Service
 metadata:
+  namespace: kube-system
   name: kube-scheduler-prometheus-discovery
   labels:
     k8s-app: kube-scheduler