🐞[BUG] Pagination not working properly in contracts view

[ds-crehm]

Description

Found on E2E:
The pagination is not working properly for the contracts API.

Current behaviour

On some pages in the contract view of the administration section, the amount of contracts shown is not correct:

On the bottom of the table it says 10 items per page and 'showing 21-30' but in the table there are only 7 contracts.

The request sent by the frontend is correct:

But in the response it says 'pagesize: 10' but it only contains 7 objects.

Expected behavior

The correct amount of objects is returned by the API (10 in this case).

Steps to reproduce the Bug

1. Log in as admin
2. Open contract view in administration section
3. Switch pages to a page with less than 10 items

Links

Might be related to #890