avb: check vbmeta digest matches property am: 7a29595ab5

Original change: https://android-review.googlesource.com/c/platform/test/vts-testcase/security/+/2927631

Change-Id: I7056c891bd905cb0d1607293501582d5a61aea1f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>