Documentation of the delegation of removal of breaking changes

### User story

We should have a documentation guideline how we want to split up the work for migrating our code to newer features within the teams. It should be in a way which they can plan it timely but also enforcing it without interrupting their roadmap.

### Acceptance criteria

- Evaluating the best approach to migrate the large codebase to newer features
- Clear documentation how areas should upgrade their code responsibilities
- Automatic CI tests to ensure that areas are aware of the changes and that the changes will be done

The issue names no files or tests. Start by evaluating how the large codebase should migrate to newer features and how teams can plan and own that work. Define the team responsibilities and planning guidance, then establish CI checks for awareness and completion; done means both the guideline and automatic checks are in place.

Written by the indexing model from the issue text.