Don't show per-monitor options if there aren't any

[jkeljo]

If you have a monitor without any pulse counters, today we just show an empty dropdown in the per-monitor options flow. We ideally shouldn't show the per-monitor flow at all, or should make it clearer that it's pulse counter options, or something.

[jkeljo]

Actually it seems like this might only apply for migrated configs; brand-new setup have config entry info for all of the pulse counters.