Stop harvesting from DataSpace

[kelynch]

Remove the DataSpace dependencies from PDC Discovery, once the migration of PRDS research data from DataSpace to PDC is complete and all migrated datasets are live in PDC Discovery.

Removing this dependency should hopefully stop a proliferation of errors around DataSpace availability in Honeybadger like this one.

This ticket is blocked until we confirm with our PO that PRDS is ready to stop harvesting from DataSpace.

Acceptance criteria

• The dspace harvesting task no longer runs as part of harvesting into PDC Discovery