Add no_slot_switch flag to update_device script am: 8212f53f9d am: ce2345dd4a am: 2ef8b5e529

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/1498858

Change-Id: I03dabfe90ec30698afc4ecb0f08f7e984904504f