[automerger skipped] Set FLAG_IMMUTABLE flag on FirstScreenBroadcast...

[automerger skipped] Set FLAG_IMMUTABLE flag on FirstScreenBroadcast PendingIntent. am: 6a7a7f6b am: 3c3e3e07 am: 5785789d am: 1d41f93c am: 7f721c7f -s ours am: 8b38024f -s ours

am skip reason: Merged-In I8d8e38a1aa6bdf13879d460cfa84cabe6c6bb1f2 with SHA-1 b62fba0d is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/14651127

Change-Id: Iec20a43b85796da44d17dc27490c4d2d0d0593a6