Lab `worldcup` can fail checks with low `N`

[KatherineCox]

For worldcup, you can fail checks if your number of simulations N is low.

I had N at 10 when I ran check50 and it gave me this error:

:( correctly reports team information for Women's World Cup
    did not find team England

Since I was only adding teams to the count dictionary if they won, I guess with the low N value there was enough variability that expected teams didn't show up. Since N is hardcoded in the python script, it might be helpful to have a hint/reminder to set it back up to something higher when submitting.

Edit: Checks can also fail when N is high due to timeout.