This prepares for using network emulation manager in Scenario tests. Bug: webrtc:9510 Change-Id: I6ae1b21790d0bcd2b01a3b293231d0859afc1ac8 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/132719 Commit-Queue: Sebastian Jansson <srte@webrtc.org> Reviewed-by: Artem Titov <titovartem@webrtc.org> Cr-Commit-Position: refs/heads/master@{#27623}