[FIX] website_profile: fix leaderboard / top3 computation

Contains some small fixes

  * correctly order leaderboard by descending karma, not creation date;
  * top 3 users displayed in footer banner should be published, otherwise
    displayed images do not match the top 3 displayed in the page displayed
    when clicking;
  * correctly say Leaderboard is an overall leaderboard, not only limited
    to the current week;

Linked to task 2005840
Related to PR #34220