Remove ProxyResolver from update_engine am: c7a1d1f288

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2168667

Change-Id: Ie3ce9438925ff71ef1a4f01c8a62bdfc759d384d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>