Inconsistent Handling of Config ID in Benchmark Class

[LabChameleon]

Hi Everyone,

the config_id is handled inconsistently in the query and get_config method. In the former it is converted into a string and in the latter it is not.

Please compare:

https://github.com/automl/LCBench/blob/17e63756b927cb814bad3275640f8be12639820a/api.py#L31-L39

versus

https://github.com/automl/LCBench/blob/17e63756b927cb814bad3275640f8be12639820a/api.py#L108-L112