_Ideally_, we would just want to export it as ECMAscript module.

For now, to support both, we can use a shared JSON file.

It would be nice to use the `import cfg from "./config.js" assert { "json" };` but
that is experimental.

The config itself will need to be updated again once the repo is
shifted to OSS GitLab, but this removes `ci/templates` for now.

The latter hasn't yet been published, and isn't available on the
OSS GitLab yet.