ovnk, virt, periodics: use 4.99 CNV since 4.21 is not out yet on this layered product

Signed-off-by: Miguel Duarte Barroso <[email protected]>

Author: maiqueb

ci-operator/config/openshift/ovn-kubernetes/openshift-ovn-kubernetes-release-4.21__periodics.yaml

@@ -109,6 +109,7 @@ tests:
   steps:
     cluster_profile: equinix-ocp-metal
     env:
+      CNV_PRERELEASE_LATEST_CHANNEL: "true"
       DEVSCRIPTS_CONFIG: |
         IP_STACK=v4
       EXTRA_MG_ARGS: --host-network