Fix view leak.

The attach listener was not being removed for ephemeral launches, which
made the controller stick around and therefore its internal views.

Fix: 381467754
Flag: com.android.systemui.shared.return_animation_framework_library
Test: ran the suite with the patch and ensured the leak is gone: https://android-build.corp.google.com/test_investigate/invocation/I16500010342444730/test/TR68829539402433209/?itab=tests&redirect=http%3A%2F%2Ffusion2%2Fab45d55b-00f8-4721-aff3-44fc1663ae68
Change-Id: I1dbcc129a75249afdf2501daf8131f719af34527