[IndexService] create sample for mockup objects

[fashxp]

see also https://github.com/pimcore/demo-ecommerce/blob/master/src/AppBundle/Ecommerce/IndexService/Tenant/Config/MyOptimizedMysql.php#L37

and

https://github.com/pimcore/pimcore/blob/16a8342daa91b4a519390becab6fbd83424b45af/doc/Development_Documentation/10_E-Commerce_Framework/05_Index_Service/09_Mockup_Objects.md#L31

[github-actions]

Thanks a lot for reporting the issue. We did not consider the issue as "Pimcore:Priority", "Pimcore:ToDo" or "Pimcore:Backlog", so we're not going to work on that anytime soon. Please create a pull request to fix the issue if this is a bug report. We'll then review it as quickly as possible. If you're interested in contributing a feature, please contact us first here before creating a pull request. We'll then decide whether we'd accept it or not. Thanks for your understanding.