[TASK] Clean up DebuggerUtility

This patch cleans up the DebuggerUtility and fixing two issues:

* removes possible XSS
* makes it more readable

Resolves: #76478
Releases: master, 7.6, 6.2
Change-Id: If1a68489cd97521e90f8d76cc2810649f9642cd1
Reviewed-on: https://review.typo3.org/48472


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Helmut Hummel <helmut.hummel@typo3.org>
Tested-by: Helmut Hummel <helmut.hummel@typo3.org>