fix: disable ClusterRoleBinding creation in E2E Helm values

The Headlamp chart defaults to creating a ClusterRoleBinding, but the
ARC runner service account lacks cluster-scoped RBAC permissions. E2E
tests only need Headlamp to serve the UI — no cluster-admin required.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

deployment/headlamp-e2e-values.yaml

@@ -17,6 +17,9 @@ config:
   pluginsDir: /headlamp/plugins
   watchPlugins: false
 
+clusterRoleBinding:
+  create: false
+
 service:
   type: ClusterIP