Guard against drag and drop failures

- Hypothetical fix for the crash, if the drag listener logic is included
  in multiple views, it's possible that multiple views can try to listen
  to the drag, which will result in cleanup being called multiple times.
  Just in case, we also guard against cleaning up the surface if somehow
  the provided drag surface is not valid.

Fixes: 414168192
Flag: EXEMPT bugfix
Test: atest ExpandableNotificationRowDragControllerTest
Change-Id: I6c8a0b16503fe0964de8db2ecb63287f1360a521