Merge "Delete deleteConversationNotificationChannels from NotificationManagerService." into sc-dev am: e0d69283 am: bff3a22c

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/13997625

Change-Id: I6cdc9e8ff0127cd3ab6077c58081d8e0aa83bae9