switched from using percentages in resetgame check

match will get cancelled if 4 or more people have left the server

vote will start if 2+ players from a team leave, or if 3 players in
total leave (3 players total is probably redundant, since it will
probably always catch that 2+ players have left from a team, but
whatever)

these checks run when the RoundEnd event gets called, so it's not
instant when players leave (though I could probably put it in
client_disconnect to make the restarting / voting happen instant if the
threshold gets met)