Remove NeutronVlanHa test from thread_3

Remove NeutronVlanHa from thread_3 because we run it in ha_neutron group

Change-Id: Ie5914e9201ac202ae0b8ac0d0a87211e0f1ae886
Closes-bug: #1395705
(cherry picked from commit a3e02c8f61274e19ffb04503dae4ff0d9e2b23f0)