Merge "Bluetooth: Mark unaudited PendingIntents with FLAG_IMMUTABLE" am: 86e190a6e9

Original change: https://android-review.googlesource.com/c/platform/packages/apps/Bluetooth/+/1560669

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ie6ecb32befaa8e807a683a0384493048383586d9