[BUGFIX] Use proper language label for hidden headlines in preview

A wrong label was used when using "Fluid based page module".
This resulted in "[]" instead of "[Hidden]" for records with hidden
headline.

This is fixed by using the proper label reference.

Resolves: #91628
Releases: master, 10.4
Change-Id: I7749cbf4441335f8493eadbb9386d95835dff9a9
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64850


Tested-by: Björn Jacob <bjoern.jacob@tritum.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Björn Jacob <bjoern.jacob@tritum.de>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>

typo3/sysext/backend/Classes/Preview/StandardContentPreviewRenderer.php

@@ -64,7 +64,7 @@ class StandardContentPreviewRenderer implements PreviewRendererInterface, Logger
             $hiddenHeaderNote = '';
             // If header layout is set to 'hidden', display an accordant note:
             if ($record['header_layout'] == 100) {
-                $hiddenHeaderNote = ' <em>[' . htmlspecialchars($this->getLanguageService()->sL('LLL:EXT:lang/Resources/Private/Language/locallang_core.xlf:labels.hidden')) . ']</em>';
+                $hiddenHeaderNote = ' <em>[' . htmlspecialchars($this->getLanguageService()->sL('LLL:EXT:frontend/Resources/Private/Language/locallang_ttc.xlf:header_layout.I.6')) . ']</em>';
             }
             $outHeader = $record['date']
                 ? htmlspecialchars($itemLabels['date'] . ' ' . BackendUtility::date($record['date'])) . '<br />'