Not all available playlists are visible in the linking dialog drop-down

[Sturek]

There should be more playlists available here. Also illustrates #792

[kai-wng-uos]

When I change the default playlist in the "Test Lehrveranstaltung", the playlist disappears from the playlist menu, both when I try to add a plylist to another course and when I try to change the default playlist. As this only happens with the pre-made Kurswiedergabeliste, I assume it coul also be a test system issue?

https://github.com/elan-ev/studip-opencast-plugin/assets/152959695/bf131768-4396-4e59-80b6-2516758bdbb7

[dennis531]

This issue should be done. I created a new issue for the latter problem.