[TASK] Remove unused SystemInformationToolbarItem->getDatabaseConnection

Since the introduction of doctrine getDatabaseConnection in
SystemInformationToolbarItem is no longer used and can be removed.

Resolves: #76354
Releases: master
Change-Id: I675ada2355bfe48b93de66cea03a3f0fc290d382
Reviewed-on: https://review.typo3.org/48365


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>

typo3/sysext/backend/Classes/Backend/ToolbarItems/SystemInformationToolbarItem.php

@@ -424,16 +424,6 @@ class SystemInformationToolbarItem implements ToolbarItemInterface
         return $GLOBALS['BE_USER'];
     }
 
-    /**
-     * Returns DatabaseConnection
-     *
-     * @return \TYPO3\CMS\Core\Database\DatabaseConnection
-     */
-    protected function getDatabaseConnection()
-    {
-        return $GLOBALS['TYPO3_DB'];
-    }
-
     /**
      * Returns current PageRenderer
      *