Fix job type assignment and clean up testfunctions file.

Updated job type to reference `experiment.type` in `processing.py` for accurate data handling. Cleaned up and streamlined `testfunctions.ipynb` by removing outdated and redundant code, improving readability and usability.

backend/app/routers/processing.py

@@ -34,7 +34,7 @@ async def job_event_generator(db: Session):
                 run_id=getattr(experiment, "run_number", None),
                 sample_name=sample.sample_name,
                 status=job.status,
-                type=getattr(job, "type", "default_type"),
+                type=experiment.type,
                 created_at=job.created_at,
                 updated_at=job.updated_at,
                 data_collection_parameters=sample.data_collection_parameters,