[FOLLOWUP][TASK] New Login Screen

- Resolve image paths equally without fal compat layer
- Remove border if background image is set
- Increase border radius

Releases: master
Resolves: #66431
Change-Id: Icf5217c46467268f67d4e7fd91903e916535ebfa
Reviewed-on: http://review.typo3.org/38926


Reviewed-by: Andreas Fernandez <andreas.fernandez@aspedia.de>
Tested-by: Andreas Fernandez <andreas.fernandez@aspedia.de>
Reviewed-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Tested-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Reviewed-by: Nicole Cordes <typo3@cordes.co>
Tested-by: Nicole Cordes <typo3@cordes.co>