Remove overscroll on keyguard when swiping up then down

This very specific set of gestures can sometimes cause the
notifications to overlap the lock icon/udfps icon after the
user stops dragging. For the migration effort, it was safer
to remove this small overscroll for the drag up/down case
then continue to support it. There is no loss of functionality.

Fixes: 329399801
Test: Swipe up slightly on lockscreen, then down
Flag: ACONFIG com.android.systemui.migrate_clocks_to_blueprint
TEAMFOOD

Change-Id: Iba86a6f233fc563f556825a14d06fc2de394fff6