Cancel Button in Upload Notification Fails to Stop Ongoing File Uploads

### ⚠️ 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. Upload multiple files
2. While the upload is in progress, open the notification panel.
3. Press the Cancel button from the upload notification. Additionally, a "Cancel All" button can be added. The action of "Cancel All" should also clear any failed uploads from the upload list.

### Expected behaviour

All ongoing uploads should be immediately stopped, and the upload process should be canceled entirely.

### Actual behaviour

The Cancel button does not stop the uploads. Files continue to upload in the background despite the cancellation action.

### Android version

15

### Device brand and model

Android Emulator

### Stock or custom OS?

Stock

### Nextcloud android app version

3.31.0

### Nextcloud server version

31.0.0

### Using a reverse proxy?

I don't know

### Android logs

_No response_

### Server error logs

```bash

```

### Additional information

_No response_