[BUGFIX] Fix labels in linkvalidator

Change the id which is referred in the label to make it
possible to toggle the checkbox by clicking on the label.

Resolves: #65564
Releases: master, 6.2

Change-Id: I4d4b8ac91b324405f5c94e2db7e6fd5205e85462
Reviewed-on: http://review.typo3.org/37587


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Nicole Cordes <typo3@cordes.co>
Tested-by: Nicole Cordes <typo3@cordes.co>