Incorrect requests to customer for item stock

[tom-rm-meyer-ISST]

Description

Current behaviour

We currently search the item stock in the DTR by partner material number for customers. Likely @ReneSchroederLJ has been right and we have an issue in stocks in this service.

Expected behavior

manufacturerPartId in the end should be ownMaterialNumber for calls against customers.

Steps to reproduce the Bug

int seed setup and log out the DTR request.