Fixing notification background peeking from the bottom when expanding QS

The issue was caused by notification scrim shifted 1px upward to overlap quick settings scrim.
That was needed because of aliasing issue - but checking now that shouldn't be really required as a long as we have horizontal overlapping still in place.
Additionally, this 1px vertical shift might be causing other misalignment issues also when notification scrim is fully visible and views are aligned to the scrim's top.
Before (with 1px shift): https://screenshot.googleplex.com/3sWpkb7Zn7W8hQk
After (no shift): https://screenshot.googleplex.com/AardmjvDezgGC9Q

Fixes: 190767217
Bug: 186644628
Test: see screenshots
Change-Id: Ie5ead80aa51f838716f1b355d439f36dd7c3c41b