Allow loading custom Groovy extension modules

[essobedo]

Description

To fix a memory leak, Groovy is declared as a parent first artifact in Quarkus core, consequently when Groovy tries to load the existing extension modules, it loads them from the System ClassLoader instead of the Quarkus Runtime ClassLoader so it cannot see the Groovy extension modules that are not part of Groovy itself.

The goal of this improvement would be to find another way to fix the leak so that Groovy is no more a parent-first artifact.

Implementation ideas

One way to fix both problems (leak and custom extension modules) is to simply disable the usage of ClassValue in Groovy

[essobedo]

A potential fix #34447