Fixing QS blinking when going from unlocked to AOD in split shade

The issue is no longer visible after some recent changes, but the core issue still remains: while transitioning from unlocked to AOD, alpha was following panel expansion while it should follow (newly named) mLockscreenToShadeProgress.
This change doesn't modify things visually now but makes alpha as expected so likely to prevent this issue resurfacing in the future.

Fixes: 246945311
Test: manual + QSFragmentTest
Change-Id: I3762b2969d22dc500f5b63f222e059800117c168