App moved into background on lock when passcode is set

### ⚠️ 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. set up app passcode for Netcloud client app
2. open *All files* tab
3. lock device
4. wait more than 5 seconds
5. unlock device

### Expected behaviour

Nextcloud app prompts user for pin entry.

### Actual behaviour

Nextcloud app has been moved into background and user is presented with launcher instead.

Opening the app manually will prompt for pin entry. This is a UX/flow design problem.

### Android version

11 (AOSP image)

### Device brand and model

Google Pixel 2 (Android Studio Emulator)

### Stock or custom OS?

Stock

### Nextcloud android app version

c35b63e

### Nextcloud server version

28.0.3

### Using a reverse proxy?

No

### Android logs

_No response_

### Server error logs

_No response_

### Additional information

> [This line](https://github.com/nextcloud/android/blob/stable-3.28.0/app/src/main/java/com/owncloud/android/authentication/PassCodeManager.kt#L153) causes the app to be moved to the background when the timeout is reached. When a user locks their phone with the Nextcloud app running, they will be back at their home screen, when the phone is unlocked again. I'm not sure whether this behaviour is desirable or not. [...]