Update longhorn namespace

clusters/kairos/longhorn/kustomization.yaml

@@ -1,6 +1,7 @@
 apiVersion: kustomize.config.k8s.io/v1beta1
 kind: Kustomization
-namespace: kube-system
+namespace: longhorn-system
 resources:
+- namespace.yaml
 - helmrepo.yaml
 - helmrelease.yaml