Demote logs for NR band and duplex spacing

Demote logs to debug: they don't provide that much information, and show periodically in the UE. They are not useful.

Refactor some code to make it shorter, while we are here.

I think I have seen these logs pop up multiple times in the past. Now we have that at the workshop (with complete beginners), and it is simply a distraction. It does not provide much information.