Reduce VABC memory usage am: e47767a5a8 am: b65182410a

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2592048

Change-Id: Iaa1f9d784a1a04dc12eea69cf83591d08ebc4c0c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>