update_engine: remove unused header am: ffae5016ab am: 5d015c7fc7

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/3297876

Change-Id: I6b005f17f6670275f69aeef632a6891b71f3e8d1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>