Remove deprected functions from EncodedImageCallback and RtpRtcp

Removed EncodedImageCallback::Encoded() and RtpRtcp::SendOutgoingData().
These methods should no longer be used anywhere and it's safe to remove
them.

BUG=chromium:621691

Review-Url: https://codereview.webrtc.org/2405173006
Cr-Commit-Position: refs/heads/master@{#14923}

webrtc/modules/video_coding/video_receiver.cc

@@ -270,8 +270,8 @@ int32_t VideoReceiver::Decode(uint16_t maxWaitTimeMs) {
     if (qp_parser_.GetQp(*frame, &qp)) {
       encoded_image.qp_ = qp;
     }
-    pre_decode_image_callback_->Encoded(encoded_image, frame->CodecSpecific(),
-                                        nullptr);
+    pre_decode_image_callback_->OnEncodedImage(encoded_image,
+                                               frame->CodecSpecific(), nullptr);
   }
 
   rtc::CritScope cs(&receive_crit_);