source_administration is not used anymore on Compute Node

slapos_subscription_request: hardcode automated ledger category for the newly created sale packing list

slapos_subscription_request: hardcode automated ledger category for the newly created accounting transactions

XXX TODO check if some are missing

XXX TODO fix broken TALES expression which prevent entering invaludated/suspended

XXX FOrces tests to fail as much as possible if ledger is not configured.
Add test to ensure constraint is configured

This reverts commit abfebc9b.

This reverts commit dc667e94.

Needed for accounting