Fix odd jumps during clear all animation

The observed odd jumps during clear all are caused by scrollY position of NSSL. This CL limits setOwnScrollY on clear all animation just like closing(b/20105405 -> ag/20105405).

Flag: NONE
Bug: 269061244
Test: atest com.android.systemui.statusbar.notification.stack.NotificationStackScrollLayoutTest & manual: put many notifications with dismissible and non dismissable, click Clear All, observe no jumps during animation.
Change-Id: Ic7d09ab54bb45ea3fb57c9650939653ada23f0b3
2 files changed