Remove unused code in update.go am: 8c36631fa0

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2995682

Change-Id: I84d398db485ecc4db75dbb2e6b22374eceae9cae
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>