Suppress recent tasks updates while applying a window container transaction

- Applying a transaction may result in numerous intermediate changes
  to the window hierarchy which can result in numerous intermediate
  recent task list changes. Instead we should only notify after all
  the changes have been applied

Bug: 437981160
Flag: EXEMPT bugfix
Test: atest RecentTasksTest WindowOrganizerTests
Change-Id: I52adfbaf77eda71df1af52ee46b7e2e1c8fcd350