ipatests: fix healthcheck test without DNS
    
    ipa-healthcheck has added a new check for ipa-ca record
    missing. The test needs to be adapted to handle the new check.
    
    Fixes: https://pagure.io/freeipa/issue/9459
    
    Signed-off-by: Florence Blanc-Renaud <flo@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>