Reland "Remove the injectable bitrate allocation strategy API."

This is a reland of 80cb3f6db622442b6360e67851e8903aa0d06d03

Original change's description:
> Remove the injectable bitrate allocation strategy API.
>
> This removes PeerConnectionInterface::SetBitrateAllocationStrategy()
> plus a ton of now-dead code.
>
> Bug: webrtc:10556
> Change-Id: Icfae3bdd011588552934d9db4df16000847db7c3
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/133169
> Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
> Reviewed-by: Niels Moller <nisse@webrtc.org>
> Reviewed-by: Sebastian Jansson <srte@webrtc.org>
> Commit-Queue: Jonas Olsson <jonasolsson@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#28523}

TBR=kwiberg@webrtc.org

Bug: webrtc:10556
Change-Id: Ic17a7a7cc447292306876ee9582ad62fd2499765
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/145900
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28585}
diff --git a/video/BUILD.gn b/video/BUILD.gn
index a2cf13a..89c1f32 100644
--- a/video/BUILD.gn
+++ b/video/BUILD.gn
@@ -100,6 +100,7 @@
     "../rtc_base:stringutils",
     "../rtc_base:weak_ptr",
     "../rtc_base/experiments:alr_experiment",
+    "../rtc_base/experiments:field_trial_parser",
     "../rtc_base/experiments:keyframe_interval_settings_experiment",
     "../rtc_base/experiments:quality_scaling_experiment",
     "../rtc_base/experiments:rate_control_settings",