[Dev options][Wallpaper flag] Update all usage of enableDesktopWindowingWallpaperActivity
flag to use DesktopModeFlags

Test: Current tests pass
Bug: 348193756
Flag: com.android.window.flags.show_desktop_windowing_dev_option
Change-Id: Ib1b1b01f6a94b4d9c49019a31d0e2269246c301b
5 files changed