Remove the query parameter for retired locales

[franktopel]

Referring to https://github.com/orgs/mdn/discussions/147

Whenever I as a user of a German-language browser access any MDN page I get this annoying query parameter in the URL: ?retiredLocale=de

Since I regularly check with MDN docs and c&p links to relevant pages, this keeps me having to remove this from the URL manually.

Is there a technical necessity to have this query parameter in place? I'm kindly asking to remove that.