Adds connection: close to test server am: 59ad273151 am: 37d6f3c322 am: 749dbef88b am: 18826fbcb2

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/1422235

Change-Id: Ic2f9aa9a64aae4e15978931d9363d697c0acd89b