django/models: Ensure OIDCUser model will not be created in database
OIDCUser model will not be persisted to django database as those information are already stored in the identity provider one.
So ensure no table for the model will be created in django database by setting the auto_created meta flag to True.
Related to swh-web#3150 (closed)
Migrated from D5309 (view on Phabricator)