It's now defined in swh.scheduler

Otherwise, we are failing unicity constraint.

Related to T2070

Related bb5d405

This happens if swh.scheduler.celery_backend.config isn't imported
before the CLI runs.

Related to 56d7cff6

This also modifies the test dataset to filename with url decoded filename.
As this is what the latest pytest plugin requires.

That fixes the `swh lister run --lister debian` cli entrypoint.

By adding a `retries_left`

Instead of the old origin dict. That's what the debian loaders (old and new)
expect.

Related T2023

Related T2023

Related D2145 proposition

within the scheduled task.

Related D2135

This is no longer shared between the new debian loader and the lister.

The swh.storage.schemata module is still part of the swh.storage module though.
As this is still a dependency for the current swh.loader.debian production
loader. This will be cleaned up later.

Related D2135

The celery.shared_task decorator allows late-binding of tasks to any celery app,
which is well suited for our "task plugin" architecture.

Related T2032

Related T2032