fix(ml): pass model_root_dir to OcrOptions for RapidOCR compatibility (#28610)

* fix(ml): pass model_root_dir to OcrOptions for RapidOCR compatibility

Fix a TypeError (Path(None)) when the OCR model is invoked, caused by an upstream change in RapidOCR v3.8.1 (RapidAI/RapidOCR@8ea9626).
RapidOCR now internally calls `Path(cfg.get("model_root_dir"))`. Since `model_root_dir` was missing from `OcrOptions`, it evaluated to `None` and triggered a `TypeError: argument should be a str or an os.PathLike`.
This fix adds the missing `model_root_dir` argument to prevent the error.
Ref: #28331

* fix(ml-test): update OCR tests for RapidOCR schema change

* chore(ml-test): remove unused `cache_dir` parameter from `TextRecognizer`

* Revert "chore(ml-test): remove unused `cache_dir` parameter from `TextRecognizer`"

This reverts commit 007ad7b3f22b0c93cfc237509b460eb6d5c51075.

* fix(ml): use self.cache_dir for model_root_dir in OcrOptions