Merge "Add FLAG_IMMUTABLE to PendingIntent in LegacyModeSmsHandler." into pi-dev am: 44b02956c4 am: 06572a0820 am: 5625595e77 am: 0642423c12 am: 30d5474b58 am: e178da4943 am: 80706f5bd6 am: f0feda371a

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

Change-Id: If0b2ce9cb51e0fd0284bbc05d5539e3f11d0733d