Pause background ingestion until we get more local storage space

The main objstorage is almost out of disk space (4.x TB left).

We have ordered some more storage in August, but the preparation of the order is taking longer than we anticipated.

We need to stop background ingestion (and leave high priority jobs like save code now and the deposit enabled) until we're able to extend the main storage.

---

Migrated from T2656 (view on Phabricator)