[TASK] Center text in infobox vertically

In case an infobox has an icon but no title and the text is just one
line, the text is now vertically centered.

Also remove the css property "vertical-align: middle" as it has no
effect anymore.

Resolves: #93998
Releases: master
Change-Id: I58c75fb6c7004101a9598307ac8385a023fd2426
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/68890


Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>