Use `CONSTANT_LIST.copy` in list config fieds
See https://github.com/huggingface/datasets-server/pull/1508#discussion_r1265658458

In particular `get_empty_str_list` should not be used anymore. Same with `default_factory=list`
Use `CONSTANT_LIST.copy` in list config fieds: See https://github.com/huggingface/datasets-server/pull/1508#discussion_r1265658458

In particular `get_empty_str_list` should not be used anymore. Same with `default_factory=list`