DownloadProvider: Clear notifications for deleted items

Clear notifications for Deleted items from Download list

Issue: Notifications for deleted items from the Download
list are not getting cleared and thus tapping on such
notifications causes crash (Illegal Argument Exception)

Fix: clear notifications for deleted items by adding them
in the stale list

Change-Id: I74e94ccca7ca79ec421d76023c5c894d9487e185