Description of problem:
Some CDI metrics missing a default value, so in case there is no value these metrics will not be available on Prometheus UI and therefore, a user can miss these metrics exists.

The metrics missing default values are:
kubevirt_cdi_clone_pods_high_restart
kubevirt_cdi_dataimportcron_outdated
kubevirt_cdi_import_pods_high_restart
kubevirt_cdi_upload_pods_high_restart
*this list might be longer

Version-Release number of selected component (if applicable):
4.14 but exists since lower versions.

How reproducible:
100%

Steps to Reproduce:
1. git clone git@github.com:kubevirt/containerized-data-importer.git
2. cd containerized-data-importe
3. docker login
4. export KUBEVIRT_DEPLOY_PROMETHEUS=true
5. make cluster-up
6. make cluster-sync

might not be needed:
7. sudo sysctl -w net.ipv4.ip_forward=1
8. sudo sysctl -w net.ipv4.conf.all.route_localnet=1
9. sudo iptables -t nat -A PREROUTING -p tcp --dport 9090 -j DNAT --to-destination 127.0.0.1:9090

10. ./cluster-up/kubectl.sh port-forward service/prometheus-k8s -n monitoring 9090:9090
11. login to http://localhost:9090/
12. see the metrics I mentioned are missing a value and not shown in the metrics list.

Actual results:
some CDI metrics is missing from the Prometheus UI if they have no value.

Expected results:
All CDI metrics is available and have values in the Prometheus UI.