drop last enabled on test set

[StefOe]

Thank you for providing this code!
I noticed that drop last is enabled for the test set, which can lead to wrong test metrics since a few samples might get ignored depending on the batch size.

https://github.com/hughxx/tsf-new-paper-taste/blob/c3ec59936943801943e03e26dd9f8ae20bf8f362/data_provider/data_factory.py#L19C9-L19C25