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

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

Change-Id: I0ce90d17a98e575eba350fce6718d4b43bea1638
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>