Adding test coverage for eth transport overrides am: af9daf023d

Original change: https://android-review.googlesource.com/c/platform/frameworks/opt/net/ethernet/+/1913619

Change-Id: Ic922281e080e56fe3fcd635709bd2adfc6e625c8
tree: 8ec1b571d0e18f7a08194d369bc601b3cbb43f13
  1. service-t/
  2. tests/