fix default until timestamp
fix default until timestamp

* make default timewindow 24h, not 24h + 1 second
* since this is a graphite endpoint with inclusive until,
  there wouldn't be data for a future point anyway.

replay/metrictank,raintank/metrictank,raintank/metrictank,raintank/metrictank,replay/metrictank,raintank/raintank-metric,raintank/raintank-metric,replay/metrictank,raintank/raintank-metric,replay/metrictank,raintank/metrictank