Improve cycle breaking heuristic of merge sequence algorithm am: 0ba4ca922c

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2645144

Change-Id: I2fd02aa3a290917ab15230ed0121ad79da0da7f0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>