Build service-connectivity with system_server API

As all dependencies on hidden API have been removed, build
service-connectivity against system_server_current.

Bug: 171540887
Test: device boots, has connectivity
Merged-In: I454e8a0a8d0e0f9e6d21a8e8faf5a9e299962ad4
Change-Id: I87ef0968c96272c99c787fdbc21db261acdea6aa