GO-2026-6019: Skipper: Incomplete fix for CVE-2026-50197: an oversized body can bypass OPA deny-on-presence Rego policies in github.com/zalando/skipper
LoopbackNames replaces net.DefaultResolver with a resolver that resolves
configured names to 127.0.0.1 and fails to resolve any other name.
Uses t.Cleanup to restore resolver after the test.