[!!!][TASK] RTE Remove relative path calculation options

The RTE has no calculations anymore for defining the
relPath (thus, it's always empty) and can be removed safely.

Resolves: #72666
Releases: master
Change-Id: Ie90de879efca397a81ef9d0ddd4dda53b21e8214
Reviewed-on: https://review.typo3.org/45817


Reviewed-by: Wolfgang Klinger <wolfgang@wazum.com>
Reviewed-by: Susanne Moog <typo3@susannemoog.de>
Tested-by: Susanne Moog <typo3@susannemoog.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>