[test] Prettify test histograms and move them to main mednet repo

tests/data/histograms/raw_data/histograms_hivtb_fold_0.json

...s/data/histograms/raw_data/histograms_indian_default.json

...ta/histograms/raw_data/histograms_montgomery_default.json

...ata/histograms/raw_data/histograms_nih_cxr14_default.json

...s/data/histograms/raw_data/histograms_padchest_idiap.json

...data/histograms/raw_data/histograms_shenzhen_default.json

tests/data/histograms/raw_data/histograms_tbpoc_fold_0.json

...data/histograms/raw_data/histograms_tbx11k_v1_fold_0.json

...data/histograms/raw_data/histograms_tbx11k_v2_fold_0.json

tests/test_hivtb.py

tests/test_indian.py

tests/test_montgomery.py

tests/test_nih_cxr14.py

tests/test_padchest.py

tests/test_shenzhen.py

tests/test_tbpoc.py

tests/test_tbx11k.py