message: Enable bulk restoration by default.
  This enables loading multiple tensors in single call, allowing for better buffering and reduced load on distributed filesystems.
diff: @@ -1229,7 +1229,7 @@ class Saver(object):
  The `saver_def` proto should be the one returned by the
  `as_saver_def()` call of the `Saver` that was created for that `Graph`.
  builder: Optional `SaverBuilder` to use if a `saver_def` was not provided.
  - Defaults to `BaseSaverBuilder()`.
  + Defaults to `BulkSaverBuilder()`.
  defer_build: If `True`, defer adding the save and restore ops to the
  `build()` call. In that case `build()` should be called before
  finalizing the graph or using the saver.
  @@ -1309,7 +1309,7 @@ class Saver(object):
  if not self.saver_def or context.in_eager_mode():
  if self._builder is None:
  - self._builder = BaseSaverBuilder(self._write_version)
  + self._builder = BulkSaverBuilder(self._write_version)
  if self._var_list is None:
  # pylint: disable=protected-access
  