Remove Leta search engine and migrate users to DuckDuckGo

✨ Feature

Description

⚠️ 🚨 This is confidential until announced by Mullvad (scheduled for November 10) so please don't discuss publicly until after that date. 🚨 ⚠️

Leta is going away. Here is the removal + migration plan from @ruihildt:

Can now say we'll be stopping Mullvad Leta search as a product in the near future.

I'd like to talk about his we could proceed, based on the following tentative timeline:

Nov 10: Leta announced EOL in a blog post

December 9: removal as default search engine on MB

January: forcing users with Leta to use Duckduckgo

Let me know if this sounds possible on your side.

As long as this is not publicly announced on our blog, we'd like not to have anything public on Gitlab, IRC or elsewhere.

This change will need to be

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