[automerger skipped] Support chained init_boot partition signing am:...

[automerger skipped] Support chained init_boot partition signing am: 425f7d1c am: 296ad0f1 -s ours am: b6fad795 -s ours am: 6ad6cbf1 -s ours

am skip reason: Merged-In I65fc7913089ae318d90df55a533d3e2ebd93b029 with SHA-1 acf1b3af is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/build/+/20486714



Change-Id: I211325fb3d5100c1f3183a2f6de22ac90377f721
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>