Reset slot switch before deleting snapshots am: f92fe255d2 am: 4914d02c6d am: 2bf4ea0455

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2510838

Change-Id: I97e191bd8abf2055126a4f45aab5718f12e18bbb
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>