Merge "align metrics to 5min bundary We use one alarm clock for all pulled atoms...

Merge "align metrics to 5min bundary We use one alarm clock for all pulled atoms. If metrics from different configs are not aligned, the clock will be set to repeat at higher and higher frequency, and consume a lot of battery. Current implementation assumes a 5min minimum bucket size. New metric start time is set to be aligned to the start time of statsd in the next 5min. So it will ignore events up to 5min."