Pressing back on the home screen does not exit app when in the first run activity

### ⚠️ 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

1. Open the app without logging in
2. Press the system back button

### Expected behaviour

The app should exit. This would be normal Android app behavior.

### Actual behaviour

The home screen is presented again.

### Android version

13

### Device brand and model

Samsung Galaxy S22 Ultra

### Stock or custom OS?

Stock

### Nextcloud android app version

stable-3.24.0, gplayDebug

### Nextcloud server version

Irrelevant

### Using a reverse proxy?

I don't know

### Android logs

[bug.log](https://github.com/nextcloud/android/files/10755578/bug.log)

### Server error logs

```bash
Irrelevant.
```

### Additional information

Server info is irrelevant, because the bug appears before connecting.