This changed the field trial so the TaskQueue based congestion
controller is opt-out rather than opt-in. This prepares for removing
the legacy version of SendSideCongestionController.
Bug: webrtc:9586
Change-Id: I2cd1ca9d3f9b6e3797c856b180790c191653b0ef
Reviewed-on: https://webrtc-review.googlesource.com/c/104521
Reviewed-by: Christoffer Rodbro <crodbro@webrtc.org>
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25055}
4ff72140e6