Form can be submitted before the file finished uploading

[ozon2]

Describe the bug
Files uploaded in the form can be missing if the user submits the form while the file is still uploading.

To Reproduce
Steps to reproduce the behavior:

1. Create a form with a file upload
2. Fill the form and upload a big file (tested with 500MB)
3. The file is shown in "Uploading" state
4. Submit the form while it's still uploading
5. Look at the form responses: the file is missing

Expected behavior
The user should not be able to submit the form while the file is uploading.

Nextcloud (please complete the following information):

• Nextcloud-Version: 33.0.0.16
• Forms-Version: 5.2.5

Smartphone:

• Device: Pixel 10
• OS: Android 16
• Browser: Firefox
• Version: 148.0.2