Use microseconds precision for timings log
What does this MR do?
Currently if we look at the bottom (lowest) timings for any *_duration_s in Kibana, you'll notice it can be 0 (even if calls to the service were made). It happens because we currently have a 2 decimal precision for seconds, so if it's a quite fast call (e.g. Redis, Web request scheduling), it can present a 0.
We have 6 (microsecond) precision for a few Go service timings, so making all existing *_duration_s on Rails/API/Sidekiq use a 6 decimal precision instead of 2 would make more sense, and that's what we accomplish here.
Edited by Oswaldo Ferreira