install: Fix missing dyndb keytab directive
    
    bind-dyndb-ldap uses the krb5_keytab directive to set the path to
    the keytab to use. This directive was not being used in the
    configuration template, resulting in a failure to start named if
    the keytab path differed from the defaults.
    
    This issue was discovered when packaging FreeIPA for Debian,
    which is one of the platforms where the path is customized.
    
    Signed-off-by: Jarl Gullberg <jarl.gullberg@gmail.com>
    Fixes: https://pagure.io/freeipa/issue/9344
    Reviewed-By: Timo Aaltonen <tjaalton@ubuntu.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>