Handle tranlucent strategy on back

The first opaque activity beneath a transparent one must not be
a finishing activity.
This prevents a wrong behaviour in case of permission requests
launched from activities after the user presses back.

Bug: 261721427
Test:  Test on apps that automatically display permission dialog
       when returning from a full screen (e.g. App Info screen)
       Run `atest SizeCompatTests`

Change-Id: I04fb0f30087fad137ee6733889bcb32498b2e898