Clean up split system user code in packages/apps/Settings/

Remove legacy code belonged to Andrometa project. Split system user
feature is always turned off now.

Bug: 137101239
Test: build, sync and reboot
Change-Id: Ieb84a6e131383dcd263a5d9b29a49dc64d905fe0

src/com/android/settings/FallbackHome.java

@@ -31,7 +31,6 @@ import android.os.Handler;
 import android.os.Message;
 import android.os.PowerManager;
 import android.os.SystemClock;
-import android.os.UserHandle;
 import android.os.UserManager;
 import android.provider.Settings;
 import android.util.Log;
@@ -166,12 +165,6 @@ public class FallbackHome extends Activity {
                     .addCategory(Intent.CATEGORY_HOME);
             final ResolveInfo homeInfo = getPackageManager().resolveActivity(homeIntent, 0);
             if (Objects.equals(getPackageName(), homeInfo.activityInfo.packageName)) {
-                if (UserManager.isSplitSystemUser()
-                        && UserHandle.myUserId() == UserHandle.USER_SYSTEM) {
-                    // This avoids the situation where the system user has no home activity after
-                    // SUW and this activity continues to throw out warnings. See b/28870689.
-                    return;
-                }
                 Log.d(TAG, "User unlocked but no home; let's hope someone enables one soon?");
                 mHandler.sendEmptyMessageDelayed(0, 500);
             } else {