[automerge] Limit the size of NotificationChannel and NotificationChannelGroup...

[automerge] Limit the size of NotificationChannel and NotificationChannelGroup 2p: b664159a 2p: 990061de

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/19697196

Bug: 241764350
Bug: 241764340
Bug: 241764135
Bug: 242702935
Bug: 242703118
Bug: 242703202
Bug: 242702851
Bug: 242703217
Bug: 242703556
Change-Id: I551aa22d9fd86f8c0e29dc9cbc793bf940e021e8