[automerger skipped] [DO NOT MERGE] Make screenshot error notification PendingIntent immutable am: 87adff69 am: 51edde2c -s ours am: eef22505 -s ours

am skip reason: subject contains skip directive

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/13519314

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I8e2c80960688d5fc8a55d264179264b709a6768e