Mobile: Accessibility: Search screen: Hide the progress bar from accessibility tools when invisible

[personalizedrefrigerator]

Summary

This pull request fixes an issue where TalkBack on Android read "Progress Bar, Double-tap to activate" as the next item in the focus order after "Clear, Button", even if the progress bar is invisible.

Related to #10795.

Testing plan

Android 13:

1. Enable TalkBack
2. Open the search screen.
3. Enter a search that produces results.
4. Move to the next item until "Clear, Button" is focused.
5. Move to the next item.
6. Verify that TalkBack reads a search result.