[critical] fix bug on carbonlink cache

Hi!
there is fix for a bug on carbon-link cache: its not downscale value for lower retention interval.
Example:
lowest precision in archive 10s, for 1d - 60s, agg method -- average. Value sent to graphite: 0.1 (10 req/s for example)
10s: 0, 0, 1, 0, 0, 1, 0.1
60s: 0.5, 0.1 // 0.1 * 60 is 60 req/s, instead of 10.
This fix disable carbonlink query for requests with step higher than lowers pointPerSecond in archive.