Resolves fdo#71781: CMIS: Default Alfresco 4 URL not working

See https://bugs.freedesktop.org/show_bug.cgi?id=71781#c5
Badfully Alfresco server test doesn't follow this (their own?) rule since the url is:
http://cmis.alfresco.com/cmisatom
and not http://cmis.alfresco.com/alfresco/cmisatom

Cherry-picked from 6e9d99332c241cf20204d9dfb772bc0168bfc460

Change-Id: I3712993db96f8544381065c71a36697207ce66e0
Reviewed-on: https://gerrit.libreoffice.org/12071
Reviewed-by: Bosdonnat Cedric <cedric.bosdonnat@free.fr>
Tested-by: Bosdonnat Cedric <cedric.bosdonnat@free.fr>
Reviewed-on: https://gerrit.libreoffice.org/12090
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>