with xlv2 format we never had to fill in checksumInfo() (#17963)

- this PR avoids sending a large ChecksumInfo slice
  when its not needed

- also for a file with XLV2 format there is no reason
  to allocate Checksum slice while reading

cmd/erasure-healing.go

@@ -714,11 +714,6 @@ func (er *erasureObjects) healObject(ctx context.Context, bucket string, object
 
 				partsMetadata[i].DataDir = dstDataDir
 				partsMetadata[i].AddObjectPart(partNumber, "", partSize, partActualSize, partModTime, partIdx, partChecksums)
-				partsMetadata[i].Erasure.AddChecksumInfo(ChecksumInfo{
-					PartNumber: partNumber,
-					Algorithm:  checksumAlgo,
-					Hash:       bitrotWriterSum(writers[i]),
-				})
 				if len(inlineBuffers) > 0 && inlineBuffers[i] != nil {
 					partsMetadata[i].Data = inlineBuffers[i].Bytes()
 					partsMetadata[i].SetInlineData()