Remove ci-management node from Vagrantfile

The ci-management node isn't used for anything. This removes it from the
Vagrantfile.
Remove ci-management role from Hiera

Since the ci-management machine is no longer required, we should make sure
Puppet doesn't attempt to deploy to this machine.
Remove Graphite

Graphite was installed on ci-management-1, but as that machine was never
used, and was failing builds, it's been removed. This removes the remnants
of Graphite, which was the only thing installed there, and Graphite was only
ever installed on that box.