Increase test coverage for VPN info sent to NetworkStatsService. am: f0932b894a

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/13425311

Change-Id: Ibea98977b36f0e9a71d47f0ec3fe4926516842f7
tree: 13184a3c8e5b6fa6fe5a319177a68d09c8cb0dcf
  1. core/
  2. services/
  3. tests/