Explore ways to consolidate Checkstyle and Codenarc errors into single file for GitHub workflow

### Issue description

https://github.com/apache/grails-core/actions/runs/17872742072

Currently on the GitHub workflow you can download a zip with a file per subproject for Checkstyle and Codenarc with success and failure, which makes it difficult to quickly find the failure.

Locally the task output links you to the failure report(s)