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

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

Change-Id: I0e834967f8983811cd0059f07b903fc03f266e67