Do not associate staring window to task for rotation change

The association was used for using consistent appearance if the
starting window is moved to an activity with different letterbox
configurations.

But if the change is from display rotation or fixed rotation, it
should follow the configuration of the current activity.

Fix: 294775946
Test: ActivityRecordTests#testTransferStartingWindowSetFixedRotation
Change-Id: I2f6698aeb8470b959c10a7f1a31aa481ea5731ea