Change message topic service to be more short.
    
    This is just so that the topic doesn't end up being super long like
    `org.fedoraproject.prod.module_build_service.module.state.change`
    
    The new value will be:
    `org.fedoraproject.prod.mbs.module.state.change`
    
    Currently, the only thing listening for this is pdc-updater, which I
    will patch.