Nuke very old test data

arkindex/process/tests/manifest_samples/.arkindex.yml

arkindex/process/tests/manifest_samples/base.json

arkindex/process/tests/manifest_samples/changed.json

arkindex/process/tests/manifest_samples/collection.json

arkindex/process/tests/ml_tools/classifier/config.yml

arkindex/process/tests/ml_tools/recognizer/config.yml

arkindex/process/tests/pdf_samples/sample.pdf

arkindex/process/tests/repository_conf_samples/empty.yml

arkindex/process/tests/repository_conf_samples/text.txt

...ex/process/tests/repository_conf_samples/wrong_format.txt

...x/process/tests/repository_conf_samples/wrong_version.yml