Veto managed bean using extension in favour of producing the config.

This is a different solution than discussed, that works quite explicitly.

By using the CDI extensions, we can hook into the discovery process and veto the registration of the class SSAConfig as a managed bean.

https://www.next-presso.com/2017/02/nobody-expects-the-cdi-portable-extensions/#processannotatedtype-event

Inspiration here: https://stackoverflow.com/a/55990362