ipa-client-install: update sssd.conf if nsupdate requires -g
    
    If dynamic DNS updates are selected, sssd will use GSS-TSIG
    by default for nsupdate.
    When ipa-client-install notices that plain nsupdate is required,
    switch sssd to use no authentication for dynamic updates too.
    
    Fixes: https://pagure.io/freeipa/issue/8402
    Signed-off-by: François Cami <fcami@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>