With this metadata key set, "GCEWindowsAgent: GCE address manager
status: disabled" will appear in the VM's serial port output during
boot.

Tested:
PROJECT=${CLOUDSDK_CORE_PROJECT} KUBE_GCE_ENABLE_IP_ALIASES=true NUM_WINDOWS_NODES=2 NUM_NODES=2 KUBERNETES_NODE_PLATFORM=windows go run ./hack/e2e.go -- --up
cluster/gce/windows/smoke-test.sh

cat > iis.yaml <<EOF
apiVersion: v1
kind: Pod
metadata:
  name: iis
  labels:
    app: iis
spec:
  containers:
  - image: mcr.microsoft.com/windows/servercore/iis
    imagePullPolicy: IfNotPresent
    name: iis-server
    ports:
    - containerPort: 80
      protocol: TCP
  nodeSelector:
    beta.kubernetes.io/os: windows
  tolerations:
  - effect: NoSchedule
    key: node.kubernetes.io/os
    operator: Equal
    value: windows1809
EOF

kubectl create -f iis.yaml
kubectl expose pod iis --type=LoadBalancer --name=iis
kubectl get services
curl http://<service external IP address>