Fixes cannot transfer splash screen view due to rotation.

The system will not transfer the splash screen view to the client if the
orientation changes during launch. Therefore, lock the screen
orientation for the test activity to prevent rotation.

Flag: EXEMPT bugfix
Bug: 400553219
Test: atest SplashscreenTests
Change-Id: I124726f7ce3123c0282c028082ef6fc07ab14250
1 file changed