Revert "storage/reflink: update snap_on_start volume size in start()"

Fixed more generally in one of the next commits ("storage/reflink:
preferably get volume size from image size").

This reverts commit c43df968d568f5738745dd299b7e210d40ab6955.

qubes/storage/reflink.py

@@ -204,7 +204,6 @@ class ReflinkVolume(qubes.storage.Volume):
         if self.snap_on_start:
             # pylint: disable=protected-access
             _copy_file(self.source._path_clean, self._path_clean)
-            self.size = os.path.getsize(self._path_clean)
         if self.snap_on_start or self.save_on_stop:
             _copy_file(self._path_clean, self._path_dirty)
         else: