Call .dup in test to fix broken master

What does this MR do?

This MR fixes a broken test in master. The change calls .dup on a class passed in to some shared_examples, as a test in this set of examples calls belongs_to on the class, thereby adding a new belongs_to relationship to the model that can break our import/export configuration checking spec.

• Issue: #205382 (closed)

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done