Merge "notification stack scroller doesn't need a11y focus" into sc-dev am: 49c7bc66 am: 0e3a87bc am: 16699a13 am: a676db92

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15692791

Change-Id: Ib9ae42a6fb432c25094ede4283a16962ca1825b7