[BUGFIX] Show system news navigation buttons

Due to CSS changes in Boostrap 5 the navigation buttons
on the login screen were invisible.

This patch makes them visible again.

Resolves: #93258
Releases: master
Change-Id: Ifdd9dcb88504428303ac7680106c721038181505
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/67402


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Richard Haeser <richard@richardhaeser.com>
Tested-by: Benjamin Franzke <bfr@qbus.de>
Reviewed-by: Richard Haeser <richard@richardhaeser.com>
Reviewed-by: Benjamin Franzke <bfr@qbus.de>