[BUGFIX] Cast port to integer when setting up the database

Ensure env variable from port is cast to integer
when setting up TYPO3 with Environment variable
TYPO3_INSTALL_DB_PORT.

Resolves: #103826
Releases: main, 12.4
Change-Id: Ibd982690d3eec0527f452cd7353bdc0bf1a572c4
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/84204


Tested-by: Benni Mack <benni@typo3.org>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Benni Mack <benni@typo3.org>