refactor: do some internal refactor, and reduce the number of bufferred intermediate blocks.

source/libs/executor/src/executor.c

@@ -355,7 +355,7 @@ int32_t qCreateExecTask(SReadHandle* readHandle, int32_t vgId, uint64_t taskId,
     goto _error;
   }
 
-  SDataSinkMgtCfg cfg = {.maxDataBlockNum = 10000, .maxDataBlockNumPerQuery = 5000};
+  SDataSinkMgtCfg cfg = {.maxDataBlockNum = 500, .maxDataBlockNumPerQuery = 50};
   code = dsDataSinkMgtInit(&cfg);
   if (code != TSDB_CODE_SUCCESS) {
     qError("failed to dsDataSinkMgtInit, code:%s, %s", tstrerror(code), (*pTask)->id.str);