Harden the health checks node

[WillFreitag]

Is your proposal related to a problem?

After creating a new condition, one may "forget" to assign that condition to one or more probe but w/o ANY assignment, the condition is somewhat useless.

Describe the solution you'd like

It is checked at any time (design time) that a condition is assigned to at least one of the probes and if not, the user will get a hint on that.

Describe alternatives you've considered

Additional context