fix(system-upgrades): Add temporary broad networkpolicy

This patch adds a broader networkpolicy for system-upgrades namespace,
which should ensure network access within the namespace.

bootstrap/system-upgrades/kustomization.yaml

@@ -3,3 +3,4 @@ kind: Kustomization
 namespace: system-upgrade
 resources:
   - https://git.shivering-isles.com/github-mirror/rancher/system-upgrade-controller/-/raw/v0.8.1/manifests/system-upgrade-controller.yaml
+  - ../../shared/networkpolicies/allow-from-same-namespace.yaml