Correct hostname for OVN agent

Currently Devstack uses short hostname for configuration of OVN.
This leads to inability to start instances (failing port binding)
on hosts with full hostnames (including dots). Open vSwitch expects
hostname in external_ids that corresponds to one returned by
``hostname`` command.

Closes-Bug: #1943631
Change-Id: I15b71a49c482be0c8f15ad834e29ea1b33307c86
1 file changed