Run update_engine_unittests on presubmit am: fbfe4c35db am: cad8b062f0 am: 02c0a3e9a1 am: 4a7b00bdff

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2029098

Change-Id: I3e0c33d14aeb38c3d87209dce58567adcfac010a