WifiStack: Migrate to BatteryStatsManager SystemApi

Also,
a) Remove some dead code from ClientModeImpl around battery stats
usage, which is no longer relevant.
b) Remove static linking of services.core

Bug: 138806762
Bug: 142272248
Test: Device boots up and connects to wifi networks.
Change-Id: I311d2787b886449edf01f957263beaec43e136b8
20 files changed
tree: 674531ac5de238d419d71cbfdb7c107cce86b17e
  1. service/
  2. PREUPLOAD.cfg