Code review comment for ~moon127/charm-k8s-unifi-poller/+git/charm-k8s-unifi-poller:multi-controller-support

Discussed IRL the question of up_ - there are other valid values we'd want to pass in besides up_unifi_controller_$blah (e.g. up_influxdb_interval), so checking for up_ makes sense. Agreed to switch to urlparse to avoid hard to read regex for the URLs though.