This change ensures that neutron relies on the same logic as libvirt
to generate hypervisor hostname, to fix imcompatible hostname format
used in Nova and Neutron for resource provider name in some
configuration pattens like the one generated by TripleO.
Closes-Bug: #1926693
Change-Id: Iea2533f4c52935b4ecda9ec22fb619c131febfa1
(cherry picked from commit 577217c52d)