Merge "Save the notification group key on the bubble" into sc-dev am: 70b6c098

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/13484220

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ibb8779b1d7b01f8a552ed05e105d3de468274897