Add feature flags in OTA manifest to tune VAB behavior am: 96975b7b6d am: 5904027c2f

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2320284

Change-Id: Ie882b4672017f000446777d08db66de481888df4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>