Parameters like "slave instance list" are very similar to SlapOS Master
reserved slave_instance_list (and slapos.cookbook:slapconfiguration
slave-instance-list) and using them leads to confusion so instead prepare
to use CDN specific frontend-list as the parameter name which shall be passed.

extra_slave_instance_list is still sent as is, in order to being able to drop
it in future iterations of deployed clusters, the new parameter comes in for
future compatbility, and frontend-list is already used and understood by the
instance-slave-list.cfg.in

Change how defaults are handled in the cluster:

 * master instance handles all defaults for all nodes
   * it is the one place with all defaults
   * depending on parameter style default is global for the cluster or can be
     specified per node with -frontend-config-<i>-parameter
 * kedifa and frontend nodes need everything to be passed, in order to
   simplify the request
 * configuration. defaults are dropped, as their scope is too large - they are
   not only defaulting the value on the master, but on each requested node
   which leads to extreme complexity of parameter passing

This is required simplification, as the cluster needs full control over
defaults on each level.

This can be helpful when comparing measurements or more generally when
trying multiple versions

this is a wrapper independent from where the part got installed

no reason to have an exception here.

CPU temperature promise will now come from monitor SR

See https://firewalld.org/documentation/configuration/firewalld-conf.html#ipv6_rpfilter

When re6st is running with tunnels, the IPv6 packets can come in through
an interface and go out through another. This is expected.

See merge request nexedi/slapos!1388