Checkpoint update progress before pausing am: 42f81b8390

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2240808

Change-Id: I0858248e594af980c977fbc868e64e22e5e7fd3c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>