[BUGFIX] Correctly replace error code placeholder

Fixes a regression, introduced in #94315 and
restores legacy placeholder in cases it is used
in custom error messages, set via TypoScript.

Resolves: #95008
Related: #94315
Releases: master
Change-Id: I59b95d9d311be81faa73ae14d48f97584882f5fd
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/70771


Tested-by: Jochen <rothjochen@gmail.com>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Jochen <rothjochen@gmail.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>