Include configuration of RH-SSO 7.5.0 to Server config migration tests

The server-config-migration tests include all configuration files for each new minor version of Keycloak/RH-SSO. After releasing RH-SSO 7.5.0, it'd be great to also test the configuration for this version of the product in order to ensure all future migrations are successfully completed. 

Community issue, which will be closed, because in the upstream, there's no need to include it there.