Add wallpaper team as OWNERS for wallpaper aconfig

Bug: 365991991
Change-Id: If34ed61991278ab877952a758aae066c5b4df3e7
Test: builds with `m`
diff --git a/core/java/android/app/OWNERS b/core/java/android/app/OWNERS
index adeb045..cd7e40c 100644
--- a/core/java/android/app/OWNERS
+++ b/core/java/android/app/OWNERS
@@ -112,6 +112,7 @@
 
 # Wallpaper
 per-file *Wallpaper* = file:/core/java/android/service/wallpaper/OWNERS
+per-file wallpaper.aconfig = file:/core/java/android/service/wallpaper/OWNERS
 
 # WindowManager
 per-file *Activity* = file:/services/core/java/com/android/server/wm/OWNERS