Remove handling of install-guide/config-reference for Pike
Remove handling of install-guide/config-reference for Pike

We do not version the install-guide anymore, remove this setup from
doc-tools-check-languages.

Also, remove handling of config-reference, it does not exist anymore.

Remove handling of draft languages, we do not version any guides and
thus don't need this.

Change-Id: Ib9a231764b84eed015521c9a8b2397965760adab

openstack/openstack-doc-tools,openstack/openstack-doc-tools