fix: Add JMTEB Clustering datasets

[awinml]

Checklist for adding MMTEB dataset

Part of #749

Changes Made:

Adds the Livedoor News and MewsC-16-ja datasets from JMTEB.

---

• I have tested that the dataset runs with the mteb package.
• I have run the following models on the task (adding the results to the pr). These can be run using the mteb -m {model_name} -t {task_name} command.
  • sentence-transformers/paraphrase-multilingual-MiniLM-L12-v2
  • intfloat/multilingual-e5-small
• I have checked that the performance is neither trivial (both models gain close to perfect scores) nor random (both models gain close to random scores).
• If the dataset is too big (e.g. >2048 examples), considering using self.stratified_subsampling() under dataset_transform()
• I have filled out the metadata object in the dataset file (find documentation on it here).
• Run tests locally to make sure nothing is broken using make test.
• Run the formatter to format the code using make lint.
• I have added points for my submission to the points folder using the PR number as the filename (e.g. 438.jsonl).

[isaac-chung]

Looks great! Thanks for adding this. Can add points for review as well.