Remove WallpaperPicker2 BuildCompat

packages/apps/WallpaperPicker2 has its own copy of BuildCompat,
supposedly to allow overriding the SDK version in tests, but that
feature is never used and having an extra copy causes more work
every time the platform version is updated or finalized.  Remove
it and use checks against android.os.Build.VERSION.SDK_INT instead.
Future checks against development versions should use the offical
androidx.core.os.BuildCompat.

Bug: 186121492
Test: m WallpaperPicker2
Change-Id: I2c92e97219d01d439da5b8b49a7c1da8e34984e2
diff --git a/src/com/android/wallpaper/module/DefaultWallpaperPersister.java b/src/com/android/wallpaper/module/DefaultWallpaperPersister.java
index 0060f99..4892e6a 100755
--- a/src/com/android/wallpaper/module/DefaultWallpaperPersister.java
+++ b/src/com/android/wallpaper/module/DefaultWallpaperPersister.java
@@ -28,6 +28,7 @@
 import android.graphics.Rect;
 import android.graphics.drawable.BitmapDrawable;
 import android.os.AsyncTask;
+import android.os.Build;
 import android.os.ParcelFileDescriptor;
 import android.util.Log;
 import android.view.Display;
@@ -41,7 +42,6 @@
 import com.android.wallpaper.asset.BitmapUtils;
 import com.android.wallpaper.asset.StreamableAsset;
 import com.android.wallpaper.asset.StreamableAsset.StreamReceiver;
-import com.android.wallpaper.compat.BuildCompat;
 import com.android.wallpaper.compat.WallpaperManagerCompat;
 import com.android.wallpaper.model.WallpaperInfo;
 import com.android.wallpaper.module.BitmapCropper.Callback;
@@ -695,7 +695,7 @@
                         && mWallpaperPreferences.getWallpaperPresentationMode()
                         == WallpaperPreferences.PRESENTATION_MODE_ROTATING
                         && !wasLockWallpaperSet
-                        && BuildCompat.isAtLeastN()) {
+                        && Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                     copyRotatingWallpaperToLock();
                 }
                 setImageWallpaperMetadata(mDestination, wallpaperId);
@@ -785,7 +785,7 @@
         }
 
         private void setImageWallpaperHomeMetadata(int homeWallpaperId) {
-            if (BuildCompat.isAtLeastN()) {
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                 mWallpaperPreferences.setHomeWallpaperManagerId(homeWallpaperId);
             }