Allow core tests to use hidden connectivity API

The tests currently use hidden connectivity APIs to exercise network
stats for bandwidth or benchmarking tests.

Bug: 197717846
Test: m
  (cherry-picked from ag/16773484)
Change-Id: I8f84d57360da34315d2388cb71b3d3738b4f483e
Merged-In: I8f84d57360da34315d2388cb71b3d3738b4f483e