[BUGFIX] Correct the replace section of sysext:lang

The extension name and folder is lang, not language.

Change-Id: Ieb11fa16af67a9e203c3c4e5dc96acca5501567f
Resolves: #81733
Releases: master, 8.7, 7.6
Reviewed-on: https://review.typo3.org/53348


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>