Wait for all of associated activities done animating

Fixed rotation transform was finished and continued
to update the orientation when transferring the
starting window, which was before the activity ready to
show and caused flickers. This can happen while trampoline
activities were started during app launch.

This also fixes other flickers that happens when the
fixed rotation launching app's animation finished
before other associated activities.

Bug: 157446341
Test: atest DisplayContentTests AppWindowTokenTests
Change-Id: Ibeb50edc7dfd9dddffe2c420fde92c1ebb70ed37