Revert "Reland "[Battery]: Delay start of TaskQueuePacedSender.""

This reverts commit dd4d5e36c6205457add1fd9df9061ca60d315fe7.

Reason for revert: crashes due to uninitialized pacing_bitrate_
crbug.com/1190547

Original change's description:
> Reland "[Battery]: Delay start of TaskQueuePacedSender."
>
> This is a reland of 89cb65ed663a9000b9f7c90a78039bd85731e9ae
> Reason for revert: failing trybots: https://ci.chromium.org/ui/p/chromium/builders/webrtc.fyi/WebRTC%20Chromium%20FYI%20Win8%20Tester/7757/overview
>
> Original change's description:
> > [Battery]: Delay start of TaskQueuePacedSender.
> >
> > To avoid unnecessary repeating tasks, TaskQueuePacedSender is started
> > only upon RtpTransportControllerSend::EnsureStarted().
> >
> > More specifically, the repeating task happens in
> > TaskQueuePacedSender::MaybeProcessPackets() every 500ms, using a self
> > task_queue_.PostDelayedTask().
> >
> > Bug: chromium:1152887
> > Change-Id: I72c96d2c4b491d5edb45a30b210b3797165cbf48
> > Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/208560
> > Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
> > Reviewed-by: Henrik Boström <hbos@webrtc.org>
> > Reviewed-by: Erik Språng <sprang@webrtc.org>
> > Cr-Commit-Position: refs/heads/master@{#33421}
>
> Bug: chromium:1152887
> Change-Id: Ia4fae13294472160e2dff40738b6fd245700beeb
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/211920
> Reviewed-by: Erik Språng <sprang@webrtc.org>
> Reviewed-by: Artem Titov <titovartem@webrtc.org>
> Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#33491}

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: chromium:1152887, chromium:1190547
Change-Id: I8ce3ba2fee8a38f918e20db953ce1c4b923cdd18
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/212700
Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33528}
diff --git a/call/rtp_transport_controller_send.cc b/call/rtp_transport_controller_send.cc
index 540fb02..f5adae6 100644
--- a/call/rtp_transport_controller_send.cc
+++ b/call/rtp_transport_controller_send.cc
@@ -133,6 +133,9 @@
   initial_config_.key_value_config = trials;
   RTC_DCHECK(bitrate_config.start_bitrate_bps > 0);
 
+  pacer()->SetPacingRates(
+      DataRate::BitsPerSec(bitrate_config.start_bitrate_bps), DataRate::Zero());
+
   if (absl::StartsWith(trials->Lookup("WebRTC-LazyPacerStart"), "Disabled")) {
     EnsureStarted();
   }
@@ -493,14 +496,9 @@
 }
 
 void RtpTransportControllerSend::EnsureStarted() {
-  if (!process_thread_started_) {
+  if (!use_task_queue_pacer_ && !process_thread_started_) {
     process_thread_started_ = true;
-    pacer()->SetPacingRates(
-        DataRate::BitsPerSec(
-            bitrate_configurator_.GetConfig().start_bitrate_bps),
-        DataRate::Zero());
-    if (!use_task_queue_pacer_)
-      process_thread_->Start();
+    process_thread_->Start();
   }
 }