Push wallpapers on the back during transitions

Fix: 350617801
Test: Manual, verify wallpaper stays on the back when opening app pair
Test: Manual, unlock device with separate lock/home  wallpapers
Flag: com.android.window.flags.ensure_wallpaper_in_transitions
Change-Id: Ie6bd4d18bfe67ca27b791a666d5b0bff6199773c
1 file changed