This flag has gone unused for a long time, time to clean it up. While we're here, convert NackRequester to use unit types. Bug: webrtc:8624 Change-Id: I1f314f9b5b6771d4f9c351a7a9a887130b86907c Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/267408 Commit-Queue: Erik Språng <sprang@webrtc.org> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Cr-Commit-Position: refs/heads/main@{#37400}