Joining a Jitsi audio-only conference uses camera

### Steps to reproduce

1. Join a multi-user room
2. With Element Web, click the telephone icon in the top-right to start a Jitsi conference call
3. See that the Jitsi widget creation event set `"data": {"isAudioOnly": true}`
4. Join the conference with Element Web, and notice that only your microphone input is used
5. Join the room with Element Android, then join the Jitsi conference

### Outcome

#### What did you expect?
When joining the Jitsi conference from Element Android, only microphone input should be used, as the conference is audio-only.

#### What happened instead?
Camera input gets used in addition to micrphone input. The camera can be turned off manually, but only after having joined after having sent a few moments of camera footage to the conference.

### Your phone model

Samsung Galaxy S8

### Operating system version

Android 9

### Application version and app store

1.3.7 from Google Play

### Homeserver

Personal homeserver

### Will you send logs?

No