Fix flicker when swiping to shade or QS

This CL fixes the check done in NotificationScrollingStack to understand
if the current scene is invisible even if it is composed. This can
happen when using alwaysCompose.

Before this CL, we would check the lifecycle of the Content, but this
lifecycle is updated in a SideEffect and therefore later than the first
composed frame when starting a transition.

After this CL, we directly check the source of truth (the
SceneTransitionLayoutState) so that it is consistent with what is
composed by STL.

Bug: 437888180
Fixes: 437888180
Test: Manual, swiped down the shade from Gone & LS
Flag: com.android.systemui.scene_container
Change-Id: I45d2ccaa4bd51862d4d0bc69f6a027ace95c224e