4.x: Only use builder API for configuration metadata for blueprints and fix processor

[tomas-langer]

Refactor all blueprints to only use API from helidon-builder-api instead of helidon-config-metadata
The features are aligned. If there is something that seems not possible, please check with the team.

This should allow us to remove the config metadata API from dependencies of such projects.

Simplify the config metadata processor, as it currently must support three parts:

1. "pure" config metadata usage on any type
2. config metadata usage on blueprints (this should be removed)
3. builder API on blueprints