REFACTOR(goldilocks): use managedNamespaceMetadata for namespace labels

- Remove namespace.yaml files
- Add managedNamespaceMetadata with Goldilocks label
- Set CreateNamespace=true in syncOptions
- Update kustomization.yaml to remove namespace.yaml references

vault/kustomization.yaml

@@ -1,6 +1,4 @@
 apiVersion: kustomize.config.k8s.io/v1beta1
 kind: Kustomization
-
 resources:
-  - namespace.yaml
-  - cluster-secret-store.yaml
+- cluster-secret-store.yaml