fix: board minutes collation: no longer try to reuse year

previously, this script fetched https://www.apache.org/foundation/board/calendar.html to re-use its style and the 'list of years' paragraph. However, presumably due to changes to calendar.html, this has been showing a random different paragraph on the minutes pages, currently 'Meeting times vary'. Instead of being clever, I don't think we have a strong need to have that year paragraph here, so we'd be better off just replacing the main content wholesale.