Resolve hidden connectivity methods dependency

This commit resolves the dependency under batterystatstests,
servicestests and coretests with hidden connectivity module codes.
Because of connectivity modularization work, the hidden connectivity
methods are not accessible outside modules. Update tests with
alternative ways.

Bug: 182859030
Test: atest
Change-Id: I8294ae4167ee5f95137e0be0f7464429ed3f3322