国标推流一直打印 'Already existed a same track' (#3713)

https://github.com/ZLMediaKit/ZLMediaKit/pull/3689 
https://github.com/ZLMediaKit/ZLMediaKit/issues/3702#issuecomment-2222326053

src/Rtp/Decoder.cpp

@@ -85,6 +85,9 @@ DecoderImp::DecoderImp(const Decoder::Ptr &decoder, MediaSinkInterface *sink){
 #if defined(ENABLE_RTPPROXY) || defined(ENABLE_HLS)
 
 void DecoderImp::onStream(int stream, int codecid, const void *extra, size_t bytes, int finish) {
+    if (_finished) {
+        return;
+    }
     // G711传统只支持 8000/1/16的规格，FFmpeg貌似做了扩展，但是这里不管它了
     auto track = Factory::getTrackByCodecId(getCodecByMpegId(codecid), 8000, 1, 16);
     if (track) {
@@ -92,6 +95,7 @@ void DecoderImp::onStream(int stream, int codecid, const void *extra, size_t byt
     }
     // 防止未获取视频track提前complete导致忽略后续视频的问题，用于兼容一些不太规范的ps流
     if (finish && _have_video) {
+        _finished = true;
         _sink->addTrackCompleted();
         InfoL << "Add track finished";
     }