Merge "Add FLAG_IMMUTABLE to PendingIntent in LegacyModeSmsHandler." into pi-dev am: 44b02956c4 am: 06572a0820 am: 5625595e77 am: 0642423c12 am: a6351932b9 am: 7495bd62c7 am: adf351e352 am: b82eff3558

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Dialer/+/16199731

Change-Id: I0db20998b180459f1e5d3a71f03f0130d015906a