Currently it's using master repo for CentOS 8. RDO s updating the version of
OVS in master to 2.13 while previous releases use version 2.12 so it's a
problem to install 2.13 for jobs gating reviews for Train or Ussuri.
This review is moving to use Train repository to install openvswitch in
all CentOS 8 jobs as it's the older version supported on CentOS 8. Note
that CI jobs running with this multi-node setup configure proper repos for
the tested release (ussuri, victoria or master) at a later stage and
update the version of OpenvSwitch to the one included on each specific
release repo.
Closes-Bug: #1896469
Change-Id: Ie30997f360b285131cb5051d582da2a15cca7205
1dbba7f70e