[TASK] Remove conf.php from ext:setup

Resolves: #63585
Releases: master
Change-Id: Id2f94cc304841a9fbe2e9422ca6519b4a7d9afab
Reviewed-on: http://review.typo3.org/35062
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>