Changing path of Xcode Server
First, make sure you are looking at the right apache config.  Base OS X includes a config file, but the one used in Server is at /Library/Server/Web/Config/apache2/sites.  

The two lines that makes Xcode the default is in 0000_any_80_.conf:

DocumentRoot "/Library/Server/Web/Data/Sites/Default"
DirectoryIndex index.html index.php /xcode/ /wiki/ default.html


That means Apache will look for an index first in /Library/Server/Web/Data/Sites/Default, but if there isn't an index file, it will try to use /xcode/ as the index (and will fall back to the wiki after that).

To override it, all you need to do is put some content in index.html. After that, you will still be able to access Xcode server in http://host.name.tld/xcode