Calculate result service map years dynamically

[mikkohei13]

At least NAFI result service aggregates observations based on year, at https://laji.fi/project/MHL.6/stats?time=all

Now the years are hardcoded. Calculate them dynamically instead:

• current year
• 5 years
• 5
• 5
• 10
• infinity

Same aggregation is used on beta search, so update that as well, unless the beta search has been updated to a completely new version. https://laji.fi/observation/finnish

See https://luomus-ict.slack.com/archives/CQEQSQCP7/p1738234169591969?thread_ts=1737968899.505339&cid=CQEQSQCP7