Simple jobs have difficulty 100
After a backfill on 2024/02/03, we got a lot of new jobs, and in particular, a lot of them have a high difficulty, much higher than what they should reach.

<img width="643" alt="Capture d’écran 2024-02-05 à 10 41 58" src="https://github.com/huggingface/datasets-server/assets/1676121/35a31d46-451f-476f-9691-01b7d302df23">

Simple jobs have difficulty 100: After a backfill on 2024/02/03, we got a lot of new jobs, and in particular, a lot of them have a high difficulty, much higher than what they should reach.

<img width="643" alt="Capture d’écran 2024-02-05 à 10 41 58" src="https://github.com/huggingface/datasets-server/assets/1676121/35a31d46-451f-476f-9691-01b7d302df23">
