Revert "Reland "Turn on WebRTC-TaskQueuePacer by defualt.""

This reverts commit 3a1051204fbe8aa6700f5a770435e48eef7218e5.

Reason for revert: Seems to cause another VideoSendStreamTest (SwitchesToScreenshareAndBack) to intermittently deadlock on Mac. 

Original change's description:
> Reland "Turn on WebRTC-TaskQueuePacer by defualt."
>
> This is a reland of b251145e38fdd08fe7320b0ddb3ca0f698473fa5
> Flaky test has been disabled, see webrtc:13294
>
> Original change's description:
> > Turn on WebRTC-TaskQueuePacer by defualt.
> >
> > Bug: webrtc:10809
> > Change-Id: If58ae3d9debc69ee68e6aeb6cecf010e60f6426f
> > Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/233580
> > Reviewed-by: Christoffer Rodbro <crodbro@webrtc.org>
> > Commit-Queue: Erik Språng <sprang@webrtc.org>
> > Cr-Commit-Position: refs/heads/main@{#35145}
>
> Bug: webrtc:10809
> Change-Id: Id76e9396f2f639caee51cf1cd895ae6deac4e259
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/235662
> Reviewed-by: Evan Shrubsole <eshr@webrtc.org>
> Commit-Queue: Evan Shrubsole <eshr@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#35237}

TBR=webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com,eshr@webrtc.org,sprang@webrtc.org

Change-Id: Idad7023b0595c6cfefa7c866091d3ed014a49839
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:10809
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/235720
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35242}
diff --git a/call/rtp_transport_controller_send.cc b/call/rtp_transport_controller_send.cc
index 9d27b33..f7b6b11 100644
--- a/call/rtp_transport_controller_send.cc
+++ b/call/rtp_transport_controller_send.cc
@@ -89,7 +89,7 @@
       bitrate_configurator_(bitrate_config),
       pacer_started_(false),
       process_thread_(std::move(process_thread)),
-      use_task_queue_pacer_(!IsDisabled(trials, "WebRTC-TaskQueuePacer")),
+      use_task_queue_pacer_(IsEnabled(trials, "WebRTC-TaskQueuePacer")),
       process_thread_pacer_(use_task_queue_pacer_
                                 ? nullptr
                                 : new PacedSender(clock,