Add new test for validation of ZFCP multipath configuration

[ilmanzo]

After #poo105440 that enabled a new multipath topology on S390x, this test validates the updated infrastructure

• Related ticket: https://progress.opensuse.org/issues/105449
• VR: https://openqa.suse.de/tests/9315250#step/validate_zfcp_multipath/7

[jknphy]

the goal is not validate the infrastructure but to know if the installer handle properly zfcp+multipath, it might be ok to do this early validation during installation but the validation should go in the installed system IMO or I am missing something...?

[ilmanzo]

quote from the ticket: "The idea is to check the status of the known infrastructure, and the status of multipathing on top of it."

as the installation does not make any use of multipath block devices, and given there's already the ZFCP validation in place, we can surely move this test after the reboot step ...

[jknphy]

LGTM, good job, looks very clear to dissect problems now.
waiting for VR succeded to merge (please, set to WIP if you want me to stop the merge due to you are performing some late minute changes or something, and remove the WIP when you are finished)