Update Grails-Forge-UI so it can be published on https://grails.apache.org/start/

[jamesfredley]

Currently includes assets which will be blocked by ASF CSP policy.

Update publishing based on https://github.com/apache/grails-static-website/blob/master/.github/workflows/publish.yml

The Google Cloud Run containers for each version also only have CORS set for start.grails.org. This will be fixed when we move these to AWS subaccount at ASF.

https://github.com/apache/grails-core/blob/7.0.x/.github/workflows/forge-deploy-next.yml#L95