Remove setOutlineProvider call from layout pass

To reduce risk of double taxation in layout-and-measure stage, move call
to setOutlineProvider in StackScrollerDecorView from onLayout to
onFinishInflate.

Test: atest com.android.systemui.statusbar
Bug: 231054525
Change-Id: Ia7a69323a3da283baabc61aa17219eac8ed9ca66