preset traffic_sign=maxspeed: Use direction icon same as other traffic_sign presets

[tordans]

The preset for traffic_sign=maxspeed was the only one in the traffic_sign preset list that used the maki square icon, which is the default "no icon" icon (at least in GoMap).

This PR changes the icon to use fas-directions which is what the other generic icons use.

FYI, the square Icon is on the maxspeed preset since the start of this repo.

Previous:

[github-actions]

🍱 Preview the tagging presets of this pull request here: https://pr-968--ideditor-presets-preview.netlify.app/id/dist/#locale=en.

[tyrasd]

yeah, the icon was like that from the very first version of the preset in iD (see openstreetmap/iD@cd8be8b). I assume this was chosen because it somewhat resembles the shape of speed limit signs found in the US, Canada and Liberia. I guess we could have a regional copy of the preset with the square icon for these countries… 🤔 //edit: done in 5c68954