dns: get_reverse_zone: Ignore resolver's timeout
    
    The DNS server may not process a query in a its internal timeout for
    a some reason or don't answer for a query at all. This may indicate
    a high load on DNS server. For example, if IPA DNS server is
    configured with 'none' forward policy (read as resolver), then
    SERVFAIL/Timeout errors will be normal until the hot cache for zones.
    Resolver's timeout in turn, indicates that it queried a server, but
    didn't received an answer in specified timeout.
    
    Related: https://pagure.io/freeipa/issue/7397
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>