Fix category mismatch

[kavigupta]

make it so you don't need to make distance_from_features and climate_change special cases. also maybe we need to handle 2010 and 2000 better. Currently the category list is only used for CSV export and juxtastat.

def get_statistic_categories():
    """
    Map from internal statistic names to categories.
    """
    category_by_tree = {}
    for category_id, category in statistics_tree.items():
        for _, group in category["contents"].items():
            for year, stats in group["contents"].items():
                for stat in stats:
                    category_id_to_use = {
                        "distance_from_features": "feature",
                        "climate_change": "climate",
                    }.get(category_id, category_id)
                    category_by_tree[stat] = (
                        category_id_to_use if year in {2020, None} else str(year)
                    )
    return category_by_tree