Rudder

When the hostname or policyserver id of a node, all rules on the node get updated, forcing all nodes with these rules to have their promise regenerated.

The idea seems to be that "we can't know where the variables were used, so let pessimistic (but correct) and force update everywhere".

I'm pretty sure that:
- we could check if really, a rule was using them
- only update theses rules

Because in the real life, node properties are very rarelly used in user directives. So in general, that change only matter for system rules (and likelly only one of them).
It is tampered by the fact that node properties change rarely, but nonetheless, it seems to be a major optimisation to have.

On a higher level, it's stupid that a local change to a node force update EVERYWHERE, because expected reports are by rule and not node.

So: make more fine grained check about what rules are impacted by node properties change.