fix(gallery): do not return overrides and additional config (#4768)

When hitting /models/available we are intersted in the model
description, name and small metadatas. Configuration and overrides are
part of internals which are required only for installation.

This also solves a current bug when hitting /models/available fails if
one of the gallery items have overrides with parameters defined

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>