Use NetdUtils instead of NetworkManagementService in Vpn

NetdUtils has the same method(e.g. setInterfaceUp) as
NetworkManagementService so using the one inside NetdUtils instead
and try to remove NetworkManagementService from Vpn in
the following commit.

Bug: 170598012
Test: atest FrameworksNetTests
Change-Id: I867556478fbc8c8ca8baa4e4c438a47b3beebe39