Showing Fellow Jitster for guests in Jitsi

### Steps to reproduce

1. Start a jitsi call.
2. Join the call from the guest invite link.
3. Check on Android and see "Fellow Jitster"

### Outcome

#### What did you expect?
A config on Android to build this with a custom string or maybe just a more general term like - "guest"
#### What happened instead?
Fellow Jitster is shown, would be better to not show Jitsi related stuff.

I think the sdk needs to be rebuilt for this? I found two tickets on Jitsi but they seem to not have any leads:
https://community.jitsi.org/t/change-fellow-jitster-to-guest-user-in-ios-sdk/113686/6?u=chagai_friedlander
https://community.jitsi.org/t/change-fellow-jitster-labels-on-ios-with-self-hosted-jitsi-meet-installation/82924

### Your phone model

Xiaomi 11

### Operating system version

Android 11 RKQ1.200826.002, MIUI 12.5.6.0 (RKQEUXM)

### Application version and app store

private fork

### Homeserver

private server

### Will you send logs?

No

### Are you willing to provide a PR?

No