[TASK] Remove backPath calculations from Reports module

Use PathUtility:.getAbsoluteWebPath() to link to the
deprecation log.

Resolves: #73764
Releases: master
Change-Id: Ie0e0fc063d2ad9ab1a43dfe4128ac351ea9fa1be
Reviewed-on: https://review.typo3.org/46972


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>