Fix wrong color of clock in preview in picker

Bug: 378720500
Flag: NONE bugfix
Test: manual test previewing different wallpaper for default clock,
metro clock and new flex clock, observing that color is correctly
updated. Also review b/332961021 and confirm that it doesn't reproduce.

Change-Id: Ia5b056041ceb4ffecbabd735b7b2a98c7a267730