wicked: handle coredump of unknown source

[cfconrad]

If there are coredumps, but not related to wicked, we should not fail in before_test module.

• Failed job: https://openqa.opensuse.org/tests/3705475#step/before_test/44
• Verification run: https://openqa.opensuse.org/tests/3705628

[github-actions[bot]]

Great PR! Please pay attention to the following items before merging:

Files matching lib/**.pm:

• [ ] Consider adding or extending unit tests in t/

This is an automatically generated QA checklist based on modified files.

[dzedro]

This broke on 12-SP5 https://openqa.suse.de/tests/14836518#step/before_test/202