Generated application.yml should not hard code info.app.* values

[matrei]

Description

The info.app.name, info.app.version and info.app.grailsVersion configuration values should not be hard coded in the generated grails-app/conf/application.yml file.

In earlier versions of Grails these values where set in application.yml as:

info:
  app:
    name: '@info.app.name@'
    version: '@info.app.version@'
    grailsVersion: '@info.app.grailsVersion@'

In Grails 6 they are set as:

info:
  app:
    name: g610
    version: '0.1'
    grailsVersion: 6.1.0

I believe it's preferable to return these values to placeholders, eliminating the need for updates in multiple locations. It would be even better if we in the future could remove them from the application.yml file, as they contribute unnecessary clutter without providing any value for the developer. But removing them now, for some reason, makes them unavailable in production environment.