Fixed the navigation bar placement on device restart.

Moved logic that adjusts the hotseat position from the constructor of
the NavbarButtonsViewController to onTaskbarLayoutChange() method that
is called from the TaskbarViewController TaskbarView layout change
listener.

Test: Manual:
Moved the bubble bar to the default right position. Rebooted the device.
Navigation bar was placed on the left side of the screen.
Flag: com.android.wm.shell.enable_bubble_bar_in_persistent_task_bar
Bug: 367829539

Change-Id: Ife0c48a72b318d6051b7b09bde13818546e65d98