Fix neutron-ovn-tempest-ovs-master-fedora job
Fix neutron-ovn-tempest-ovs-master-fedora job

The job should use OVN_BRANCH = master and OVS_BRANCH = master,
because based on its definition, it should use master code.

Change-Id: I0a708ae63d6a2c8933324157a4bbbd229fc43073
Related-Bug: #1877377

mahak/neutron,openstack/neutron,openstack/neutron,openstack/neutron,mahak/neutron,mahak/neutron