Use autogenerated StatsLog that is Q-friendly

Statsd is introducing new APIs in R for StatsLog.
This change generates two different versions of
NetworkStackStatsLog.java, one that can be compiled using strictly Q
APIs and below, and another one that uses new APIs.

Generated NetworkStackStatsLog that only uses Q APIs:
https://paste.googleplex.com/5195949209026560

Generated NetworkStackStatsLog that uses new APIs:
https://paste.googleplex.com/5741370595606528

Bug: 148388745
Test: m NetworkStack
Test: m NetworkStackNext
Change-Id: Ibf47157dec0a9b9bddb45b6ec9c17806e6a29565