Revert "Merge "Add netd support for configuring IPv6 optimistic mode." into lmp-mr1-dev"
This is to undo ag/569594.
This reverts commit 828f8b88, reversing
changes made to ac7fefcf.
Bug: 18609055
Bug: 17769720
Change-Id: I120745d9d01d731174f477dff9b463dede8523d7