Correct vulnerability when setting pending intents on import/export notifications by setting FLAG_IMMUTABLE am: 1d595f80e9 am: 835bc188db am: 2aedd25d2e

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Contacts/+/12272170

Change-Id: Ia4cca9a1832384c9742b6a7e9108a5d5e94781f6