Merge "build_image: Query the actual image size after invoking the final...

Merge "build_image: Query the actual image size after invoking the final mkfs." am: 0096a750 am: 965ca0d9 am: f301d211 am: 161afa9b

Original change: https://android-review.googlesource.com/c/platform/build/+/1889816

Change-Id: I0c3d47e4d590c7d52e5a8ec431c6ec6bdb2764b2