[TASK] Change check for TYPO3_MODE

Change check for TYPO3_MODE:

if (!defined('TYPO3_MODE')) {
	die('Access denied.');
}

to

defined('TYPO3_MODE') or die();

Resolves: #60112
Releases: 6.3
Change-Id: I2b4493509c912f620a993dc4ba69c4449fcac04d
Reviewed-on: https://review.typo3.org/31338
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring