Change default current scene of test transitions

This CL is a simple change of default value in test transitions: it
usually make more sense to default the current scene to toScene and not
to fromScene.

Bug: 353679003
Test: atest PlatformComposeSceneTransitionLayoutTests
Flag: EXEMPT test only
Change-Id: If5a43f75af9447a4920c8a46eb29900c631f83f3
1 file changed