Merge branch...

Merge branch '6383-ah00548-namevirtualhost-has-no-effect-and-will-be-removed-in-the-next-release-etc-apache2' into 'develop'

Resolve "AH00548: NameVirtualHost has no effect and will be removed in the next release /etc/apache2/sites-enabled/000-ispconfig.vhost:7"

Closes #6383

See merge request ispconfig/ispconfig3!1634