update_engine: refactor into method am: 0dc25a6779 am: 0eaf2ea59d

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2932913

Change-Id: Ibd9dbea7c8806aad43ab39d4c547efd4e58818ed
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>