Speed up the dashboard feature test

I can't think of a very good reason to call `visit` 2,009 times for this
test. Changing these to more sane numbers took this test from ~8 seconds
to 0.5 seconds.

If this spec was trying to test the formatting of the numbers on the
dashboard, that would be much more simply and efficiently covered by a
view spec, but I don't find it to be to terribly interesting to test so
I didn't do that.