src: remove unused method in class Http2Stream

PR-URL: https://github.com/nodejs/node/pull/25979
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Michaël Zasso <targos@protonmail.com>

src/node_http2.h

@@ -465,10 +465,6 @@ class Http2Stream : public AsyncWrap,
 
   void EmitStatistics();
 
-  // Process a Data Chunk
-  void OnDataChunk(uv_buf_t* chunk);
-
-
   // Required for StreamBase
   int ReadStart() override;