improves TestGetSeriesCachedStore
improves TestGetSeriesCachedStore

instead of only comparing the cache hits on a subset of range searches,
we compare them on all searches.

fixes #462

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