Instead of computing the average on the device, upload the
total sum of the latencies. Server can divide by the event count
if it wants to get the average.
Also change the latency buckets to 1 hr, 2 hrs, 4 hrs, 8 hrs and
greater than 8 hrs.
Bug: 70297451
Test: launch an app
dumpsys batterystats --checkin | grep jbd,
Observe the dumped values for the app
Change-Id: Iecda808594fc960fb16fa0407e5875bbc47db43a
0ca706bb9e