grails-core groovydoc duplication for grails-data

[jamesfredley]

Issue description

If we remove the extra groovydocs from grails-data they would need to be done as part of https://github.com/apache/grails-core/issues/14990

/api/ has groovydocs for everything in grails-core including grails-data.

Duplicated Groovydocs for grails-data exist in the combined /api/ and a second location:

grails-data/api grails-data/hibernate5/api grails-data/mongodb/api

https://docs.grails.org/snapshot/api/ https://docs.grails.org/snapshot/grails-data/api/ https://docs.grails.org/snapshot/grails-data/hibernate5/api/ https://docs.grails.org/snapshot/grails-data/mongodb/api/

everything else, which was consolidated into grails core, only exists in /api/.

grails-gradle and grails-forge, are separate Gradle projects are not included. https://github.com/apache/grails-core/issues/14978 & https://github.com/apache/grails-core/issues/14996

[jamesfredley]

We will remove the extra groovy docs apis published to /grails-data/* and link all documentation there instead.