[flexiglass] Gradually reset scrim offset while expanding QS

Bug: 355286156
Test: manually verified the scrim offset increases as expansion goes to 0, eventually reaching 0 at the end of the transition.
Flag: com.android.systemui.scene_container
Change-Id: I1ea3f1a9f7869e770dd9b2aee2b3afbfb8971dc6
2 files changed