test images: Temporarely exclude Windows test images

A previous PR (kubernetes#76838) introduced the ability to build and publish
Windows Test Images to kubernetes/test/images/image-util.sh.

Additionally, that PR also configured the Image Promoter to use a
few Windows Remote Docker build nodes to build the Windows Test Images,
however, there is a minor issue: the build container has a different $HOME
folder than expected (is: /builder/home, expected: /root - since it's the
root user), and the Remote Docker credentials are mounted in /root.

Because of that, image-build.sh cannot find the credentials it needs.
This will have to be properly fixed, but for now, we can just skip
the Windows image building part.

Author: claudiubelu

test/images/cloudbuild.yaml

@@ -17,9 +17,7 @@ steps:
     - BASE_REF=$_PULL_BASE_REF
     - WHAT=$_WHAT
     - REGISTRY=gcr.io/k8s-staging-e2e-test-images
-    - REMOTE_DOCKER_URL_1809=tcp://img-promoter-1809.eastus.cloudapp.azure.com:2376
-    - REMOTE_DOCKER_URL_1903=tcp://img-promoter-1903.eastus.cloudapp.azure.com:2376
-    - REMOTE_DOCKER_URL_1909=tcp://img-promoter-1909.eastus.cloudapp.azure.com:2376
+    # TODO(claudiub): Readd the REMOTE_DOCKER_URL_${os_version} to reenable the Windows test image building process.
     args:
     - all-push
 substitutions: