Revert "XWIKI-10247: Impossible to use a rendering syntax installed as extension"

This reverts commit 15005930ef37ff114054b16424cf7e27a8b4d32a.
Revert "XWIKI-10247: Impossible to use a rendering syntax installed as extension"

This reverts commit f885ba8b13329443a679d797335bbb786ea3eb8c.