+++ This bug was initially created as a clone of Bug #1091649 +++

## Observation

When migrating older products which had SuSEFirewall2 as default to a current
product version which have firewalld by default then the SuSEFirewall2 is
preserved which is not supported anymore.

See for example scenario
opensuse-15.0-DVD-x86_64-update_Leap_42.3_gnome@64bit-2G in
[firewall_enabled](https://openqa.opensuse.org/tests/667584/modules/firewall_enabled/steps/1)
showing that SuSEFirewall2 is still active.


## Reproducible

* Upgrade pre-15 distributions (or corresponding TW version) with enabled
SuSEFirewall2 to corresponding 15-based version
* `SuSEfirewall2 status` reports that the firewall is still running


## Expected result

* **E1:** An unsupported firewall should not continue to run silently in the
background. Some error message or information to the user should be shown.


## Further details

Always latest result in this scenario:
[latest](https://openqa.opensuse.org/tests/latest?version=15.0&distri=opensuse&arch=x86_64&test=update_Leap_42.3_gnome&flavor=DVD&machine=64bit-2G)


https://openqa.suse.de/tests/1657059#step/firewall_enabled/1 shows the
corresponding SuSEFirewall2 for SLE15