[BUGFIX] Resolve duplicate array key in ext:impexp test fixture

Resolves: #96681
Releases: main, 11.5
Change-Id: I71ff411cd4cd639ad8d68dfcf02e46ac8818705d
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/73208


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>