Make test data generation reproducible am: 7c7e7faf56 am: b2d600a55e am: 6a0bf14094

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2774950

Change-Id: If84a7ab43ccc5d41daed6f67ef5d209a6bcf0e65
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>