mirror-container-images job keep repo name

There is a use case where you may want one level of /'s kept in the image name for ease if mirroring containers from multiple registries.
For example, mirroring

```
quay.io/foo/bar/debug-tooblox
ingress-nginx/ingress-controller
```

you may want your registry to have myregistry/myproject/bar/debug-tooblox and myregistry/myproject/ingress-nginx/ingress-controller