[automerger skipped] Merge "Support AVB signing for BOARD_PREBUILT_BOOTIMAGE" into sc-dev am: 22fb8a47 -s ours

am skip reason: Merged-In I7ee8b3ffe6a86aaca34bbb7a8898a97b3f8bd801 with SHA-1 cf9ead89 is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/build/+/14716393

Change-Id: Iecce38b4dd55db7e4bb097eb678625776d34e946