[TASK] Remove unused code in TYPO3\CMS\Install\SystemEnvironment\Check

Remove code which is never executed since the system environment check
of the Install Tool is omitted in cli mode.

Resolves: #64876
Releases: master

Change-Id: If22117d793b54230dc5ae703df478a91482fa7e6
Reviewed-on: http://review.typo3.org/36672


Reviewed-by: Nicole Cordes <typo3@cordes.co>
Tested-by: Nicole Cordes <typo3@cordes.co>
Reviewed-by: Michael Oehlhof <typo3@oehlhof.de>
Tested-by: Michael Oehlhof <typo3@oehlhof.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>