quota: delay throughput counter update in trieindex.throttle
quota: delay throughput counter update in trieindex.throttle

When throughput quota usage might be exhausted in a child rule, in the previous implementation,
the throughput counter would be updated immediately after the check, this might lead to over-accounting
for parent quota configs.

The comment changed the implementation to only update the counter if the traffic is confirmed
to be within quota consumption.

At the same time, go-carbon also makes sure to report throttled data points for soft throughput quota
enforcement (i.e. with "none" dropping policy).

lomik/go-carbon,deniszh/go-carbon,deniszh/go-carbon,lomik/go-carbon,lomik/go-carbon,deniszh/go-carbon