[BUGFIX] Improved visibility error message in install tool

Removed the absolute positioning of the error page to avoid unexpected
behavior when rendered in an encapsulated component, e.g. panels in the
Install Tool.

Resolves: #88064
Resolves: #87382
Releases: master, 9.5
Change-Id: I5cefeacc0f753ab57c8c1e95dffa39eb55f5950e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/60377


Tested-by: Benjamin Kott <benjamin.kott@outlook.com>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Benjamin Kott <benjamin.kott@outlook.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>