Revert "XWIKI-10021: No public access to main wiki webhome when public access is not allowed on a subwiki."

This reverts commit d3ebe25dd0349ef92f19ee557c3cc9218e0742d2.
XWIKI-10021: No public access to main wiki webhome when public access is not allowed on a subwiki.

* replace $xwiki.checkAccess() by $xwiki.hasAccess()