Dispose the embedded TFs synchronously when handle app died

So that the embedded TFs and activities are removed along with
the non-embedded activities vs. perform the disposal until the
binder died callback.

Bug: 429336735
Test: kill AE process
Flag: com.android.window.flags.dispose_task_fragment_synchronously
Change-Id: Ife2a9d8d11194f50141983bc092045636f11e398