Reset libsnapshot states before applying a new update am: c54c99646f

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2263803

Change-Id: I50c581269eddab963a4a46cf47d853483f513885
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>