Update eliot stage url

[willkg]

This updates the stage url for the service status script to the new Eliot webservices stage gke one.

You can run the script like this:

python bin/service-status.py

[willkg]

It's weird that there's lines like this in the PR history:

The language suggests something got deployed, but it didn't.

[smarnach]

GitHub Actions always writes that something has been "deployed" if you use an "environment" for a worklfow, since "environments" are meant to be used for deployments.

We are using environments to configure workload identity federation, so we can upload images to GAR without storing any actual secrets in GitHub. But once we do that, we get that weird language in PRs, and I don't think there's much we can do about this.