DSCO: Order Ingestion Cleaned Up

Two same-week fixes to how DSCO orders come into Endless.

The reference-number and customer fields were slightly off. The customer reference number on imported DSCO orders now uses the retailer's consumer order number when it's there (falling back to the DSCO order id if not), and the retailer id lands on the customer name field instead of the trading-partner name. Existing orders aren't rewritten — this fixes new imports going forward.

Separately, every DSCO order was quietly creating an empty B2B-data record even when there was nothing to store. That row is gone; B2B data is only written now when there's a retailer id to put in it.