[Dual Shade] Fix Notification Blur getting stuck

While the QS panel is already open, and we drag down from the top left corner to open the Notification panel, we didn't give a chance to this flow to reset its value to 0. This CL fixes it by simplifying the condition, and only mapping the blur fraction to qsExpansion.

Bug: 396346867
Test: Open the Notification panel while QS panel is already open
Flag: com.android.systemui.scene_container
Change-Id: I15f899968f5e65a99570ec6fcb0a416a0fa8a58e