Changed some calendar names to represent country names

[aho15]

Corresponding issue: #884
Changed calendar names to the respective country name instead of language in settings.py.

Unfortunately, due to free tier limitation, I am not able to update all calendars.
This should be done as they currently contain holidays from 2025 - 2028 instead of from 2026 - 2029 and they seem to have been last updated in 04/2025.

[janbrasna]

This has the potential to result in broken links for consumers — who would have to figure out something's wrong with their ics subscription, come back to the site, and subscribe to the correct file now… so I figure the actual tricky part of the ticket for any renaming really is the necessary addition of all the old-to-new redirects in some place as .htaccess (or its build script)…

[janbrasna]

The question is whether to also not stop turning the country names into the adjectives here in the "normalization" phase… ("Italian", "French", "German" etc. above too — as not just the calendar names earlier, but also this mapping step changes the end result too…)

[aho15]

I am sorry for costing your time. I should have seen both of these issues and at least bring them up to you.

Concerning the mapping of the filenames: I removed the entries which only led to change from country name to language. I then recognized for Algeria, it's default language was french, which made me think: why not including the default languages names in the file name as well? I think it won't hurt further and increases consistency.