Update firewalls in maintenance reconciliation

[Gerrit91]

This PR implements the set roll for firewalls when a shorthand OS image name is being used and the maintenance reconciliation was triggered.

[majst01]

Deployment does not change and therefor the imagecache will not be asked to fetch the newest image.

It should depend on the gardener maintain reconciliation and trigger firewall roll during the maintenance window

[Gerrit91]

Looks like this finally works now.