Stop maintaining finegrained mapstat table and new_location scores.

This lets us remove about 65 million records from the mapstat table,
leaving 8 million rows for the 100x100 meter metric. The finegrained
stat is too detailed to keep world-wide and we aren't using it anymore.

The `new_location` score was never exposed and counted how many times
a user entered a previously uncharted 10x10m area. This is a bad metric
and the new_cell/new_wifi scores give a good idea about discovering
new data.