Remove RTPFragmentationHeader creation and propagation through webrtc

Bug: webrtc:6471
Change-Id: I5cb1e10088aaecb5981888082b87ae9957bbaaef
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/181541
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31955}

modules/video_coding/codecs/test/video_codec_unittest.h

@@ -42,8 +42,7 @@ class VideoCodecUnitTest : public ::testing::Test {
         : test_(test) {}
 
     Result OnEncodedImage(const EncodedImage& frame,
-                          const CodecSpecificInfo* codec_specific_info,
-                          const RTPFragmentationHeader* fragmentation);
+                          const CodecSpecificInfo* codec_specific_info);
 
    private:
     VideoCodecUnitTest* const test_;