Merge "Add SysUI flag notification_clearable_refactor" into udc-qpr-dev am: de88986a14 am: 3c78e182ef

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/24146308

Change-Id: Iab2dd653c7dd7e0c0b9d9136964a7e92f4c9e2e2
Signed-off-by: Automerger Merge Worker <[email protected]>