fix: set capacity for newly created datablock

source/common/src/tdatablock.c

@@ -463,6 +463,7 @@ SSDataBlock* blockDataExtractBlock(SSDataBlock* pBlock, int32_t startIndex, int3
 
   pDst->info = pBlock->info;
   pDst->info.rows = 0;
+  pDst->info.capacity = 0;
   size_t numOfCols = taosArrayGetSize(pBlock->pDataBlock);
   for (int32_t i = 0; i < numOfCols; ++i) {
     SColumnInfoData  colInfo = {0};