Remove "router" from /install
We create the "router" (https://tails.boum.org/contribute/design/installation_assistant#index3h1) for the following reasons:
- We wanted to put forward that installing from another Tails was always much easier.
- Mac users had complicated options to choose from.
Now that we distribute USB images, the only major difference between installing from scratch from Windows and macOS and cloning Tails is the time to download the USB image. If people can clone because they already have a friend that has Tails they could also probably get a download from them, verify it and install from Windows or macOS anyway.
So I think that the extra steps and questions (and code!) behind the router are not worth it anymore.
Update: One thing the router would still be useful for is to have different cloning scenarios for people on PC and Mac as right now we have both:
Another objective might end up being to move all the installation assistant as pages under /doc. Like we started treating /doc/upgrade as the canonical resource about upgrades in #10885.