Fix EZP-22397: Page converter major testing and debug

Link: https://jira.ez.no/browse/EZP-22397

## Description
I first fixed the issue on displaying items in `restoreItemFromXml`. But then I had to provide a unit test for it.
Creating and fixing the unit test showed that other part of the converter were not working as expected so I also fixed them.

## Tests
Manual tests on EZP-22397 use case and updated unit tests.