[IMP] website_profile, website_slides: add user ranking and karma on elearning main pages

Purpose of this commit is to improve karma and gamification inclusion in
elearning [1].

 * remove a border, replaced by a standard hr, in rank template. It allows to
   reuse it easier as we don't necessarily want that border in other templates
   using it;

Commit linked to task ID 1941250 and PR #31133.

[1] task ID 1922159 (landed at 5fa651cb)