Fix JSON error in identifiers.json

[eidens]

This error didn't cause the pipeline to fail, but it did cause an incomplete prompt to be sent to the model without any database info (src/soda_curation/pipeline/data_availability/data_availability_openai.py#49):

        except Exception as e:
            logger.error(f"Error loading database registry: {str(e)}")
            return {"databases": []}

That might be the cause for the identifiers.org prefix occasionally not being used.