Try to reduce celery memory usage

• limit max tasks per child : https://docs.celeryq.dev/en/latest/userguide/optimizing.html#memory-usage
• celery ignore results ? -> we consume all results so we probably don't need that (no memory leak)
• add ignore_result when task do not return anything ?
• only keep warning logs and up
• disable sentry init in tasks.py
• change how we log info in tasks.py