Move FinishedSnapshotWrites call to filesystem verifier am: 5b00dc5386 am: d7d2ba702f

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2601565

Change-Id: Ie259de9f533bef8ba44461593deeaaa0c3c4afe2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>