Post process the collections in a given folder, reducing them in a memory preserving way.
Path to the root file of the data collection like statistics-out/top-2023-01-01-00-00-00/
statistics-out/top-2023-01-01-00-00-00/
Collection of features to post process, expects corresponding folders to exist
non-aggregated reports for each sub-key of each feature
Post process the collections in a given folder, reducing them in a memory preserving way.