fix: cattle-system namespace (#399)

- cattle-system namespace is created earlier than helm
- leave namespaces.yaml to manage cattle-system namespace (required
  before installing helm/rancher)

Reviewed-on: #399

modules/rke2/files/namespaces.yaml

@@ -1,6 +0,0 @@
-apiVersion: v1
-kind: Namespace
-metadata:
-  name: cattle-system
-  labels:
-    kubernetes.io/metadata.name: cattle-system