Revert "Use the factory instead of using the builtin code path in VideoCodecInitializer."

This reverts commit be142178aaf6ab4089b4d81c88c3d59c12cca567.

Reason for revert: breaking internal projects

Original change's description:
> Use the factory instead of using the builtin code path in `VideoCodecInitializer`.
> 
> Bug: webrtc:9513
> Change-Id: Ia299ae1044a3ff4c91e208200938cba540bdcea6
> Reviewed-on: https://webrtc-review.googlesource.com/c/94782
> Commit-Queue: Jiawei Ou <ouj@fb.com>
> Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
> Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
> Reviewed-by: Sebastian Jansson <srte@webrtc.org>
> Reviewed-by: Anders Carlsson <andersc@webrtc.org>
> Reviewed-by: Seth Hampson <shampson@webrtc.org>
> Reviewed-by: Erik Språng <sprang@webrtc.org>
> Reviewed-by: Niels Moller <nisse@webrtc.org>
> Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#25456}

TBR=brandtr@webrtc.org,magjed@webrtc.org,sakal@webrtc.org,nisse@webrtc.org,andersc@webrtc.org,tommi@webrtc.org,kthelgason@webrtc.org,sprang@webrtc.org,srte@webrtc.org,perkj@webrtc.org,tkchin@webrtc.org,shampson@webrtc.org,glaznev@webrtc.org,ouj@fb.com,qingsi@webrtc.org

Change-Id: I8040ccabe3ae6464d72c7696adb663c1dd275b63
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:9513
Reviewed-on: https://webrtc-review.googlesource.com/c/108980
Reviewed-by: Qingsi Wang <qingsi@webrtc.org>
Commit-Queue: Qingsi Wang <qingsi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25459}

modules/video_coding/codecs/test/videoprocessor.cc

@@ -14,7 +14,6 @@
 #include <limits>
 #include <utility>
 
-#include "api/video/builtin_video_bitrate_allocator_factory.h"
 #include "api/video/i420_buffer.h"
 #include "common_types.h"  // NOLINT(build/include)
 #include "common_video/h264/h264_common.h"
@@ -174,9 +173,8 @@ VideoProcessor::VideoProcessor(webrtc::VideoEncoder* encoder,
       stats_(stats),
       encoder_(encoder),
       decoders_(decoders),
-      bitrate_allocator_(
-          CreateBuiltinVideoBitrateAllocatorFactory()
-              ->CreateVideoBitrateAllocator(config_.codec_settings)),
+      bitrate_allocator_(VideoCodecInitializer::CreateBitrateAllocator(
+          config_.codec_settings)),
       framerate_fps_(0),
       encode_callback_(this),
       input_frame_reader_(input_frame_reader),