Improve tests which train model

[wochinge]

Description of Problem:
We identified a couple of tests which train models in the CI and which can be improved. This is supposed to speed up the CI as model trainings take quite some time.

Overview of the Solution:
Improve these test cases according to the suggestions. If their is no good solution attach a nofix label

Examples (if relevant):

Blockers (if relevant):
Should be done after

Definition of Done:

• Implement solutions for all issues in the needs tackling / can be tackled column which do not have a nofix label.