Remove min function call from debug statement in the clean service function

[tynanford]

@jacomago I ran into this log statement which was causing a runtime error when findSizeLimit wasn't defined in my configuration file.

First I was going to change this to self.conf.get but then it seemed like this isn't necessary here? Since get_active_channels is already called and it's returned value is the channels arg in clean_channels?

[jacomago]

LGTM