Wrong username displayed in account list

### ⚠️ Before posting ⚠️

- [x] This is a **bug**, not a question or an enhancement.
- [x] I've [searched for similar issues](https://github.com/nextcloud/android/issues) and didn't find a duplicate.
- [x] I've written a clear and descriptive title for this issue, not just "Bug" or "Crash".
- [x] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/).

### Steps to reproduce

Add an account and log-in with the e-mail-address instead just the username of the Nextcloud account.

### Expected behaviour

The correct accountname should get displayed in the account list.

### Actual behaviour

The Nextcloud account gets displayed as emailuser@emaildomain@nextcloudhost.domain.

### Android version

16 (CalyxOS 7.2.1.0)

### Device brand and model

Fairphone 4

### Stock or custom OS?

Custom (explain in "additional information")

### Nextcloud android app version

33.1.0

### Nextcloud server version

32.0.6.1

### Using a reverse proxy?

No

### Additional information