Remove hidden connectivity method usage

Becuase of modulization work for connectivity module, the
connectivity hidden methods are not accessible outside the
module. This commit replace the hidden methods usage under
ConnectivityManagerTest.

Bug: 182859030
Test: Remove framework-connectivity from the private API ; atest
Change-Id: I5e23bd0ab2e82fc3583c56162d5ac3fec6cfc359
Merged-In: I5e23bd0ab2e82fc3583c56162d5ac3fec6cfc359