Remove the usage of hidden API

- Connectivity related files will be inside mainline module, so
the external callers cannot call its hidden API. Remove the usage
of hidden API or replace it with public API.

Bug: 182859030
Test: atest FrameworksMockingServicesTests:ConnectivityControllerTest
Change-Id: I36e732b7e44aeb7e7716ef2c948b92770d458529