Fix copy from encrypted multipart to single encrypted part (#7056)

When source is encrypted multipart object and the parts are not
evenly divisible by DARE package block size, target encrypted size
will not necessarily be the same as encrypted source object.

cmd/object-handlers.go

@@ -914,7 +914,8 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 			case !isSourceEncrypted && !isTargetEncrypted:
 				targetSize = srcInfo.Size
 			case isSourceEncrypted && isTargetEncrypted:
-				targetSize = srcInfo.Size
+				objInfo := ObjectInfo{Size: actualSize}
+				targetSize = objInfo.EncryptedSize()
 			case !isSourceEncrypted && isTargetEncrypted:
 				targetSize = srcInfo.EncryptedSize()
 			case isSourceEncrypted && !isTargetEncrypted: