fix(e2e): reference shared infra RBAC instead of local file (PRI-720)

Remove deployment/e2e-ci-runner-rbac.yaml — RBAC is now managed via
Flux GitOps from privilegedescalation/infra/base/rbac/e2e-ci-runner-headlamp-rbac.yaml.

Changes:
- .github/workflows/e2e.yaml: Remove local RBAC apply steps (no longer
  applying local file); RBAC pre-flight check now verifies all required
  roles/rolebindings are present (managed elsewhere via Flux)
- scripts/deploy-e2e-headlamp.sh: Update error message to point to the
  infra repo raw URL instead of the removed local file

Co-Authored-By: Paperclip <noreply@paperclip.ing>

scripts/deploy-e2e-headlamp.sh

@@ -35,7 +35,7 @@ fi
 echo "Checking RBAC permissions in namespace '${E2E_NAMESPACE}'..."
 if ! kubectl auth can-i delete configmaps -n "$E2E_NAMESPACE" --quiet 2>/dev/null; then
   echo "ERROR: Missing RBAC — cannot delete configmaps in namespace '${E2E_NAMESPACE}'." >&2
-  echo "  Apply RBAC first: kubectl apply -f deployment/e2e-ci-runner-rbac.yaml" >&2
+  echo "  Apply RBAC from infra: kubectl apply -f https://raw.githubusercontent.com/privilegedescalation/infra/main/base/rbac/e2e-ci-runner-headlamp-rbac.yaml" >&2
   exit 1
 fi