Integration tests not run automatically for model additions

[juanmichelini]

Problem

When adding a new model to resolve_model_config.py, integration tests were mentioned but the process to trigger them was unclear and manual.

Solution

Updated ADDINGMODEL.md to document the gh workflow run command for triggering integration tests with the correct parameters.

The workflow order was adjusted to:

1. Create draft PR first
2. Run integration tests
3. Fix issues if needed
4. Mark PR ready when tests pass

See PR #2783 for the fix.

[VascoSch92]

Closing as duplicated.