Fix backfill wrong difficulties, causing OOMs
The backfill was creating duckdb indexing jobs for big datasets without adjusting the difficulty.

Because of that the medium workers were processing them and OOMing and every retry.
Fix backfill wrong difficulties, causing OOMs: The backfill was creating duckdb indexing jobs for big datasets without adjusting the difficulty.

Because of that the medium workers were processing them and OOMing and every retry.