[TASK] Correct body-Tag id in Backend

Remove the beginning dash of the id in body-Tag by
stripping the forward slash from the route identifier.

Change-Id: I1454f5f51469ea17b9bdf5520b50c8da8825a73f
Resolves: #75525
Releases: master
Reviewed-on: https://review.typo3.org/47651


Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Gianluigi Martino <gmartino27@gmail.com>
Tested-by: Gianluigi Martino <gmartino27@gmail.com>
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>