Prevent BAL from Wallpaper Picker

Background activity launch logic won't use pending intent
creator foreground state as long as the ActivityOptions have
been set up to prevent that.

This stops an app from registering itself as the handler for
ACTION_SET_WALLPAPER and sending a request to launch
itself indirectly into the foreground.

Change-Id: I4dbaee9cd85aa53d5d2aaf2e8b0734de13c1dafd
Test: BALBypassViaWallpaperChooser
Bug: 257953844