Disable celery built-in periodic task celery.backend_cleanup
    
    This task is useless and causes issue in odcs.
    
    https://docs.celeryproject.org/en/stable/userguide/configuration.html#std-setting-result_expires
    
    JIRA: RHELCMP-6814
    Signed-off-by: Haibo Lin <hlin@redhat.com>