[Split shade] Fix QS showing briefly on AOD after turning off the screen

This was caused by the SplitShadeOverScroller being invoked while on
lockscreen and setting a translationY value to 0 on QSFragment.
That class is not supposed to be used on lockscreen, therefore the fix
was to make sure it is only used on non-lockscreen.

Change-Id: I6f89303c4fcdc04c77b5b2dac8d71cf66fe08ff4
Bug: 208255733
Test: ShadeTransitionControllerTest.kt
Test: Manually