Avoid creating the same ID task multiple times

include/libs/stream/tstream.h

@@ -346,12 +346,14 @@ typedef struct SStreamMeta {
   void*        streamBackend;
   int32_t      streamBackendId;
   int64_t      streamBackendRid;
+  SHashObj*    pTaskBackendUnique;
 } SStreamMeta;
 
 int32_t tEncodeStreamEpInfo(SEncoder* pEncoder, const SStreamChildEpInfo* pInfo);
 int32_t tDecodeStreamEpInfo(SDecoder* pDecoder, SStreamChildEpInfo* pInfo);
 
-SStreamTask* tNewStreamTask(int64_t streamId, int8_t taskLevel, int8_t fillHistory, int64_t triggerParam, SArray* pTaskList);
+SStreamTask* tNewStreamTask(int64_t streamId, int8_t taskLevel, int8_t fillHistory, int64_t triggerParam,
+                            SArray* pTaskList);
 int32_t      tEncodeStreamTask(SEncoder* pEncoder, const SStreamTask* pTask);
 int32_t      tDecodeStreamTask(SDecoder* pDecoder, SStreamTask* pTask);
 void         tFreeStreamTask(SStreamTask* pTask);