[BUGFIX] Stabilize ext:impexp acceptance test

Minor refactoring of ExportCest to prevent some
not needed page tree operations in exportRecord()
may stablize that test further.

Resolves: #95182
Releases: master
Change-Id: I1d07669e47f01c191b25cc2e06f7814c254d98a8
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/71022


Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>