Close icon folder for predictive back to home animation.

Folders are typically closed in launcher#onResume. However in the
predictive back flow, launcher isn't resumed until transition fully goes
through. Therefore we need to explicitly close the folders on transition
start.

Bug: 229861300
Test: Open an opted in app from workspace folder and swipe back (with
animations enabled).

Change-Id: I4b5229cd2590c164ffba892f49eeb2e26438eadf