Possible misconfiguration when using "Take results from other Scoring"

[SSchulze1989]

Describe the bug
Since both of the source and target scoring can be configured with individual Session selection it ist possible to have the target Scoring selected a session that is not in the source Scoring. No result will be available for calculation which will lead to an error on the database.

To Reproduce
Steps to reproduce the behavior:

1. Create two scorings and two sessions
2. On the first scoring select session 1
3. On the second scoring select both sessions and scoring 1 as Results source
4. Upload results for both sessions
5. See error when trying to view results for Session 2

Expected behavior
A configuration like this should not be possible. Session selection should be limited to sessions available from the Results source.