Handle NTP configuration in a replica server installation
    
    There were two separate issues:
    
    1. If not enrolling on a pre-configured client then the ntp-server and
       ntp-pool options are not being passed down to the client installer
       invocation.
    2. If the client is already enrolled then the ntp options are ignored
       altogether.
    
    In the first case simply pass down the options to the client
    installer invocation.
    
    If the client is pre-enrolled and NTP options are provided then
    raise an exception.
    
    https://pagure.io/freeipa/issue/7723
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>