TCO21 Algo leaderboard fix

[kkartunov]

https://tco21.topcoder.com/competition-overview/algorithm/leaderboard

Should display TOTAL SCORE properly.
Rename # OF CHALLENGES to # OF MATCHES

[SathyaJayabal]

@kkartunov ,

1. Total score should be updated the top 3 cards too
2. Rename # OF CHALLENGES to # OF MATCHES on top 3 cards too