Remove oamaha related code am: 033e173e3f am: 3141621dc6 am: b760252c4c

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2747005

Change-Id: Ib064168f152e9f7dc3aa77eff3bdbb479407201d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>