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

Committed: https://crrev.com/c681250aaa2025836db7669694e323898e5c2ca7
Review-Url: https://codereview.webrtc.org/2405173006
Cr-Original-Commit-Position: refs/heads/master@{#14923}
Cr-Commit-Position: refs/heads/master@{#14935}

webrtc/test/fake_encoder.cc

diff --git a/webrtc/test/fake_encoder.cc b/webrtc/test/fake_encoder.cc
index 065b529..f518ce3 100644
--- a/webrtc/test/fake_encoder.cc
+++ b/webrtc/test/fake_encoder.cc
@@ -112,8 +112,10 @@
     encoded.rotation_ = input_image.rotation();
     RTC_DCHECK(callback_ != NULL);
     specifics.codec_name = ImplementationName();
-    if (callback_->Encoded(encoded, &specifics, NULL) != 0)
+    if (callback_->OnEncodedImage(encoded, &specifics, NULL).error !=
+        EncodedImageCallback::Result::OK) {
       return -1;
+    }
     bits_available -= std::min(encoded._length * 8, bits_available);
   }
   return 0;