Validate notification placement at transition end

When switching from large to small clock, some layout
updates are skipped with the clock transition is running
in order to smooth out notification animations. However,
the final critical update could be dropped. Ensure the
placement is sent one final time on transition end.

Test: manual - Add delayed notification when GONE, go to
DOZING, check placement (race condition here so try many
times)
Fixes: 350718118
Flag: com.android.systemui.migrate_clocks_to_blueprint

Change-Id: I2c8a170197b1bfa52abbc1271d2d6f8e924778a8