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

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

Change-Id: Ice5d545c1494a1366ae3e3b21a23eb1851892441