Screen record UI polish

- Fix capitalization
- Default to device audio
- Use showBigPictureWhenCollapsed instead of setting largeIcon
separately
- Update styles to inherit device default

Fixes: 185544094
Fixes: 185544175
Fixes: 186427367
Fixes: 185544265
Test: visual

Change-Id: Ic545f8bc0ef77aabaab24a4585c87c3aa29ac7f5