[BUGFIX] Remove debug echo from checkDeniedSuburls

Resolves: #72598
Releases: master,7.6,6.2
Change-Id: I585f5d24678f63d576a61ff779daee634c8556a8
Reviewed-on: https://review.typo3.org/45705


Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>