Wv 452 update any uses of polling location objects all that could use readonly instead of hitting main database [TEAM REVIEW]

[MadisonEvans94]

implemented control flow statements for all read operations in polling_location so that the 'readonly' db is utilized

There are a few other items that I noted that may need further review/second opinion:

• should we consider name change for update_polling_location_with_log_counts? To me, the 'update' implies that it's a CRUD action, but the method only reads from db and outputs a dictionary
• in polling_location.models.py, is the retrieve_polling_location_by_we_vote_id method redundant?
• is there a cleaner way to do the control flow? eg:

def get_queryset(model, read_only=True):
    if read_only:
        return model.objects.using('readonly').all()
    else:
        return model.objects.all()

or possibly using DATABASE_ROUTES provided by django