Trim oversized strings in setId and setConversationId

Flag: EXEMPT bugfix
Test: android.app.NotificationChannelTest
Test: cts NotificationChannelTest
Bug: 419014146
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:a9a1b4365b8d6def5b36fed7dd9caf2389fe0a51)
Merged-In: Id721d3123ee8d38753f550fe57ba0f5d15d743ac
Change-Id: Id721d3123ee8d38753f550fe57ba0f5d15d743ac
2 files changed