Revert ConnectivityServiceDependencies access modifier

Address review comment on aosp/2490881

ConnectivityServiceDependencies was made public in aosp/2490881 to
verify destroyLiveTcpSockets call.
This CL reverts that change and updates tests to use mocked
DestroySocketsWrapper to verify destroy sockets call.

Bug: 270298713
Test: atest FrameworksNetTests
Change-Id: I101016399ea29bc5176b7559edf0447f0f7901ce