Call Scene's exit action when use TransitionManager.go() with null transition

Bug: 65536124

When we pass null for TransitionManager.go() there is a special logic where we forgot to call previousScene.exit(), only newscene.enter() is called.

Test: added unit tests and tested manually
Change-Id: Ibd4d5a2cc17bbfe4aaa586357446da28d4b355af
1 file changed