Removed spammy log message from the FrameBuffer.

Inserting old frames is not an error condition and should not print a warning, and given that it happens all the time it is also very spammy.

Bug: chromium:1066819
Change-Id: Iad2b5edc5e62822c02e2bb2a53d4318f957be3bd
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/173022
Commit-Queue: Philip Eliasson <philipel@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31172}

modules/video_coding/frame_buffer2.cc

@@ -491,10 +491,6 @@ int64_t FrameBuffer::InsertFrame(std::unique_ptr<EncodedFrame> frame) {
   auto info = frames_.emplace(id, FrameInfo()).first;
 
   if (info->second.frame) {
-    RTC_LOG(LS_WARNING) << "Frame with (picture_id:spatial_id) ("
-                        << id.picture_id << ":"
-                        << static_cast<int>(id.spatial_layer)
-                        << ") already inserted, dropping frame.";
     return last_continuous_picture_id;
   }