Remove redefined macros from BitrateAdjuster

This CL removes the include that redefines Chrome macros, so Chrome
can include this header in https://codereview.chromium.org/1818903004/.

Review URL: https://codereview.webrtc.org/1824833002

Cr-Original-Commit-Position: refs/heads/master@{#12095}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 2df29cb673d38a91c6a08326ae3009aba4feae9a
diff --git a/modules/video_coding/include/bitrate_adjuster.h b/modules/video_coding/include/bitrate_adjuster.h
index 8c9143f..ec58445 100644
--- a/modules/video_coding/include/bitrate_adjuster.h
+++ b/modules/video_coding/include/bitrate_adjuster.h
@@ -14,7 +14,6 @@
 #include <functional>
 
 #include "webrtc/base/criticalsection.h"
-#include "webrtc/base/gtest_prod_util.h"
 #include "webrtc/base/rate_statistics.h"
 
 namespace webrtc {