Insufficient capacity modal on first connexion on Firefox + proxy

### Steps to reproduce

1. Where are you starting? What can you see?
On some PC configured with network restrictions (proxy, vpn, firewall etc?, not sure what is causing the issue). The first connexion using element-web pop the "Insufficient capacity" modal. The other participant can see the new member with waiting for media avatar.
Closing the call, and restarting/joining works withouth the insufficient capacity modal.

Looking at the logs, we can see it is the websocket connection to the livekit that is failing :
```
Lifecycle] Connecting & publishing index-ByQHsvE1.js:2:1792735
[Lifecycle] Connecting to livekit room wss://livekit.fr ... index-ByQHsvE1.js:2:1792735
[MatrixAudioRenderer] All audio tracks have a matching matrix call member identity. index-ByQHsvE1.js:2:1792735
silence detected on local audio track
Object { room: undefined, roomID: undefined, participant: undefined, pID: undefined, trackID: undefined, source: "microphone", muted: false, enabled: true, kind: "audio", streamID: "{d9d1bca6-7ff4-4988-aaea-26f9e32e58ec}", … }
index-ByQHsvE1.js:2:1792735
Firefox can’t establish a connection to the server at wss://livekit.fr/rtc?access_token=token.testmcmllcy1iZXRhLmdvdXYuZnI6YWdlbnQuZGludW0udGNoYXAuZ291di5mcjpCRllaVEZBQlNWIiwidmlkZW8iOnsiY2FuUHVibGlzaCI6dHJ1ZSwiY2FuU3Vic2NyaWJlIjp0cnVlLCJyb29tIjoiIUpRZWVQTXF0ZHRHdklEY3NFQTphZ2VudC5kaW51bS50Y2hhcC5nb3V2LmZyIiwicm9vbUNyZWF0ZSI6dHJ1ZSwicm9vbUpvaW4iOnRydWV9fQ.nRnqYEps6nqxTU72-AhZxD943QeybOK3MgLkZbJb3j0&auto_subscribe=1&sdk=js&version=2.15.7&protocol=16&adaptive_stream=1. index-ByQHsvE1.js:2:1109599
websocket closed
Object { room: undefined, roomID: undefined, participant: undefined, pID: undefined, reason: "", code: 1006, wasClean: false, state: 4 }
```

### Outcome

#### What did you expect?
To start/join a call directly without seing the "Insufficient capacity" modal for the first connexion

#### What happened instead?
I see the "Insufficient capacity" modal, needs to close the call and retry for it to work

### Operating system

Windows

### Browser information

Firefox 147.0.2

### URL for webapp

using element call 0.16.3 but also failing with 0.17.0

### Will you send logs?

No

Start at the first-call LiveKit connection path in element-call and reproduce the failure in Firefox with a proxy or other network restriction. Inspect the reported WebSocket error and the transition to the “Insufficient capacity” modal, then compare it with the successful second attempt. Done means the first call joins without the modal in the affected environment, with regression coverage where the project’s call tests allow it.

Written by the indexing model from the issue text.