Fixes #5888: don't display new rule with N/A compliance

I'm really not sure that we want to address that at that level: here, we are just hiding an inconsistency with a big hypothesis on it's cause. Isn't there a solution to just make the state not reachable ?

(some time latter): ok, that does not seem possible with the current modelization, because at no time in the compliance computation we use anything else then expected reports. So if we ask for compliance for a rule without expected reports for that node, we just don't get any compliance reports (see ReportingServiceImpl#buildNodeStatusReports). 

So it seems to be the best possible solution available with our unconsistant model. 

It's ok with me, just merge it when the remark done by Vincent is addressed.