Make sure the firewall rules are created even if the bridge interface is already created

The issue is that currently we set the rules (especially nat) for the bridge at the time of creation. This can lead to issues where the connectivity to the Internet from inside of the containers is lost.

This was originally reported in RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1033606. You can find there more info about it.