Merge "Make system-generated FGS notification PendingIntents immutable" into rvc-qpr-dev am: 895dbfa8ef am: 1d95dc53bc

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11708354

Change-Id: I41d30ae5f605f17e490de116c340c455dee2f2fe