virtualize.sh: redeploy the router on upgrade
virtualize.sh: redeploy the router on upgrade

Since the virt_platform.yml may change between version, we drop the
router. This way it will be redeployed with the new configuration.

This commit also introduct the drop_host() function.

redhat-cip/infra-virt,enovance/infra-virt,redhat-cip/infra-virt,enovance/infra-virt