AOSP/WallpaperPicker - update the WallpaperPicker test package version to target P (28) or higher. am: f147ac2fdb am: b50b0d2d71 am: 7e4e26fee6 am: 4fd92c6175 am: 26df17875a am: b6eff2dff2

Original change: https://android-review.googlesource.com/c/platform/packages/apps/WallpaperPicker/+/849112

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I793450e24eda10e30bd8cc9ea3465edac8dfd594