Revert "Make neutron functional job non-voting"

The Neutron functional job is running properly again after the hooks script fixes merged to master and stable/icehouse:

https://review.openstack.org/#/c/117280/
https://review.openstack.org/#/c/117281/

Enabling this job will ensure that breaking hook script changes will not be able to merge in the future.

This reverts commit 70d909536116a14f670f44ee7411552bd6e0cf2a.

Change-Id: I1f39f182d7807fcbc80ba20684ea9f0f3e935116
Merge "Revert "Make neutron functional job non-voting""