Move ending CUJ_SPLIT_SCREEN_ENTER to after we show tasks to user

* Previously the CUJ was ending after only the launcher side
animation was completing, before we actually made the
call into shell to launch the tasks

Test: Compiles (no baseline to test metrics/latency off of)
Bug: 285578568
Change-Id: I958e4a5265cb2fd81f2358343846385058b4465a