[BUGFIX] Avoid logging of invalid locales in site configuration

TYPO3's log is mostly covered with "Locale fr_FR.UTF-8 not found",
which can be simplified, if setlocale() is not working properly.
The POSIX Platform suffix "UTF-8" is then removed, and setlocale()
is called again with "fr_FR" instead of "fr_FR.UTF-8" thus avoiding
log flooding in some systems.

Resolves: #99591
Releases: main, 11.5, 10.4
Change-Id: I4609d453c29a306d448bcdc3277b51a344af28ae
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/77435


Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>