Fix model creation first step

On Nuxeo Insight for 11.x, when creating a new box, the first step fails to load the document types.

Reprodution steps on preview

Login on https://preview-nuxeo-ai-pr-237.ai.dev.nuxeo.com/nuxeo

Then go into the link: https://nuxeo-ai-dev-dev.apps.prod.nuxeo.io/nuxeo/ai/#!/?aitoken=a9541402-ec47-44a6-876c-1f6b684e447c&projectid=jira&urlCore=https://preview-nuxeo-ai-pr-237.ai.dev.nuxeo.com/nuxeo

It correctly authenticates with Insight and the above preview instance.
Click create bot.

You will get an error on both urls fetches :

https://preview-nuxeo-ai-pr-237.ai.dev.nuxeo.com/nuxeo/json/cmis
https://preview-nuxeo-ai-pr-237.ai.dev.nuxeo.com/nuxeo/api/v1/config/types

It might be a CORS configuration issue as nuxeo.url on the previewer is defined to https://preview-nuxeo-ai-pr-237.ai.dev.nuxeo.com
and it should be to https://preview-nuxeo-ai-pr-237.ai.dev.nuxeo.com/nuxeo