In order to correctly close audio dump files, TestPeers have to be
destroyed after the call is finished.
Bug: webrtc:10138
Change-Id: I948e4e1844dfbffd1eef7926a4dd4d7631dbe632
Reviewed-on: https://webrtc-review.googlesource.com/c/122301
Reviewed-by: Artem Titov <titovartem@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26661}