ipa-advise: Define the domain used when looking up ipa-ca
    
    The error message if ipa-ca can't be resolved included the
    undefined variable ${domain_name}. Since this is static anyway
    change to a python format string and hardcode the string in
    the resulting script as api.env.domain.
    
    Discovered while working on https://pagure.io/freeipa/issue/8934
    
    Related: https://pagure.io/freeipa/issue/8934
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>