[BUG] Confusing loading state in Battery Saver

Actual behaviour

Progress bar appears and animates

Expected behaviour

Nothing or non-animating circle is shown

Steps to reproduce

1. Enable Battery Saver on e.g Android 8.1
2. Enter server details, submit

Can this problem be reproduced with the official owncloud server?
(url: https://demo.owncloud.org, user: test, password: test)

Yes

Environment data

Android version: 8.1

Device model: Pixel 7 Emulator

Stock or customized system: Stock

ownCloud app version: 4.2.1

ownCloud server version: -

Additional info

I noticed that when I enable Battery Saver on Android 8.1, the indeterminate ProgressBars in the app are not properly shown. This is a known problem in Android API level <28, see e.g. this StackOverflow question. Battery Saver disables animations, also on progress bars on these versions. This is quite confusing because the loading state is not properly represented. It is fixed in later Android versions, where progress bars do appear and animate.

Looking at the code, indeterminate progress bars are created here:

className='com.owncloud.android.ui.preview.FileDownloadFragment$listenForTransferProgress$1$1', lineNumber=222
className='com.owncloud.android.presentation.files.filelist.MainFileListFragment', lineNumber=1333
className='com.owncloud.android.presentation.files.filelist.MainFileListFragment$subscribeToViewModels$10', lineNumber=601)

To fix this issue, one can check ValueAnimator.areAnimatorsEnabled() and provide a different UI element, such as a text label, when animations are disabled.

I also recorded a video, showing the bug in practice:

https://github.com/owncloud/android/assets/165037835/812ef0f0-dd02-431d-a293-7f08ba58afc4

Start by reading the indeterminate progress-bar call sites in FileDownloadFragment$listenForTransferProgress$1$1 at line 222 and MainFileListFragment at lines 1333 and 601. Reproduce the loading flow with Battery Saver enabled on Android 8.1, then verify that the loading state is represented without relying on animation.