Wean Statsd off BatteryStats: Network Power

Statsd calls were sometimes made from BatteryStats, instead of directly
from the source, as a way of getting it running quickly in P. These must
now be done properly and separately.
Note that Statsd needs to be independent of BatteryStats, in preparation
for deprecating large parts of BatteryStats.

Bug: 80308558
Test: cts-tradefed run cts-dev -m CtsStatsdHostTestCases
Change-Id: I54fa54a2dc59dfa68f0e063d7063fac423bf0bf4