refactor stuff to get hhs file paths into its own function

[elray1]

e.g., pull these lines out into a separate function such as get_hhs_file_path:

flusion/code/data-pipeline/src/data_pipeline/loader.py

Lines 302 to 312 in 3df6b5e

	if drop_pandemic_seasons:
	if as_of is None:
	file_path = 'influenza-hhs/hhs.csv'
	else:
	# find the largest stored file dated on or before the as_of date
	as_of_file_path = f'influenza-hhs/hhs-{str(as_of)}.csv'
	all_file_paths = sorted(glob.glob('influenza-hhs/hhs-????-??-??.csv', root_dir = self.data_raw))
	all_file_paths = [f for f in all_file_paths if f <= as_of_file_path]
	file_path = all_file_paths[-1]
	else:
	file_path = 'influenza-hhs/hhs_complete.csv'