DO NOT MERGE: Sample atomic network stats buckets, full poll.

When sampling network stats, always use atomic buckets instead of
interpolating.  Always poll iface and UID together so we distribute
into buckets equally.  Move stale bucket trimming to just before
writing stats.

Bug: 5321340
Change-Id: I78a2226778a79c875f3668336e39ea24a7b4d5c4
5 files changed