Finish wrapped launcher animations if impl is gone

If the runner impl is gone (since it is a weakreference), we
still need to complete the animation contract by calling the
finish callback, so do that.

Bug: 183993924
Test: atest ActivityMetricsLoggerTests
Change-Id: Idce1859f0417cb74bbb9884e0d06750539e4545e
(cherry picked from commit 8a672e15)