Remove hidden @Transport usage

NetworkCapabilities is moving to connectivity mainline module.
The hidden methods and constants accesses are not allowed
anymore for Settings, so remove the usage.

Bug: 172183305
Test: make RunSettingsRoboTests ROBOTEST_FILTER=\
      com.android.settings.network.InternetUpdaterTest
Change-Id: I3adec99748451f32698ac19bfeaeb9db43282e3e