MCR-3769 Preserve XEditor variables in XPath validation with relevant-if

[yagee-de]

Link to jira.

Pull Request Checklist (Author)

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Ticket & Documentation

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• Design decisions (if any) are explained.
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Bugfix-Specific Checks

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• Minimal code changes were made (no refactoring).
• This PR truly fixes only the reported bug.
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• A relevant test was added (if feasible).

Testing

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Multi-Repo Considerations

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