CACHE_REQ: Copy the cr_domain list for each request
    
    Let's copy the cr_domain list for each request as this list may be
    free'd due to a refresh domains request.
    
    Resolves: https://pagure.io/SSSD/sssd/issue/3551
    
    Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>
    
    Reviewed-by: Pavel Březina <pbrezina@redhat.com>