Merge "Lower per-app NotificationChannelGroup limit." into tm-dev am: 41a2d675eb

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/21080663

Change-Id: I5801c9a408d495f96e7798fcb0e18ada03185809
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>