Remove hardcoded stream-id

[MatthiasReumann]

Motivation and Context

The chat currently doesn't work. (Fortunately, not yet deployed though 😅) It is however testable for other open PRs: https://1128.test.live.mm.rbg.tum.de/

Description

Remove hard-coded stream id.

Steps for Testing

• 1 Account
• 1 Livestream

1. Log in
2. Navigate to a Livestream
3. Chatting should work.

[github-actions[bot]]

Your Testserver will be ready at https://1130.test.live.mm.rbg.tum.de in a few minutes.

Logins

| Kurs1 | Kurs2 | Kurs3 | Kurs4 | | ---------------------------------------- | ------------------------- | ------------------------- | ------------------------- | | public | public | loggedin | enrolled | | prof1 | prof1 | prof2 | prof1
prof2 | | student1
student2
student3 | student1
student2 | student2
student3 | student1
student2 |