Switch to the DuckDuckGo .onion by default

A little bit of discussion about this can be found here: https://labs.riseup.net/code/issues/6059

The last Tails release seemed to have removed the DuckDuckGO onion service as secondary search option. Was there a security or other reason why it was removed and why the HTTPS version was used?

Related issues

Related to #13599 (closed)
Has duplicate #15473 (closed)

Original created by @Kurtis on 12121 (Redmine)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information