[BUGFIX] Only load TypoScript files on directory import

Resolves: #89720
Releases: master
Change-Id: I97e7f5b0465527d3a8ebe7190e3bdf710e9d7f54
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/62353


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Steffen Frese <steffenf14@gmail.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Rémy DANIEL <dogawaf@no-log.org>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Steffen Frese <steffenf14@gmail.com>
Reviewed-by: Felix P. <f.pachowsky@neusta.de>
Reviewed-by: Benni Mack <benni@typo3.org>