[data] Remove special idiap protocol and use config option instead

pyproject.toml

src/ptbench/configs/datasets/nih_cxr14_re/cardiomegaly.py

src/ptbench/configs/datasets/nih_cxr14_re/idiap.py

src/ptbench/data/nih_cxr14_re/__init__.py

src/ptbench/data/nih_cxr14_re/cardiomegaly.json.bz2

src/ptbench/data/nih_cxr14_re/cardiomegaly_idiap.json.bz2

src/ptbench/data/nih_cxr14_re/idiap.json.bz2