Fix small clock preview overlapped with the smart space

The reason is that status_bar_header_height_keyguard is parsed as 8 in
Panther, so we replace it with SystemBarUtils.getStatusBarHeight(context)

Bug: 360905801
Test: manual test in foldable and non-foldable device, observe that
small clock and smartspace no longer overlap in wallpaper picker preview
Flag: EXEMPT bugfix

Change-Id: I9b37805d35891ad3c1542d984934c5e1efcfa874