Clean up FileSizeFormatter

Which is not used after Change I37c7b3a4b5860323cb55581b23a90f583f4af216

Fix: 364129275
Flag: EXEMPT clean up
Test: robotests
Change-Id: I0db29c77a1dd938bff53df9e5f33c95cc0fbaad4

src/com/android/settings/deviceinfo/StorageItemPreference.java

@@ -22,6 +22,7 @@ import android.content.Context;
 import android.util.AttributeSet;
 import android.widget.ProgressBar;
 
+import androidx.annotation.VisibleForTesting;
 import androidx.preference.Preference;
 import androidx.preference.PreferenceViewHolder;
 
@@ -48,6 +49,7 @@ public class StorageItemPreference extends Preference {
         setLayoutResource(R.layout.storage_item);
     }
 
+    @VisibleForTesting
     public void setStorageSize(long size, long total) {
         setStorageSize(size, total, false /* animate */);
     }