Remove AOD_IMAGEWALLPAPER_ENABLED from feature flags

The design of aod image wallpaper has changed and we don't need this
implementation any more so we remove it from feature flags.

Bug: 118470430
Bug: 123617158
Test: Manually

Change-Id: I4d48a8b6b8146b754c1d1f48c35855190219d8a9
1 file changed