Log manual poll results as INFO even if comms method is polling

[hjoliver]

The scheduler logs poll results like this:

[1/foo/01:submitted] (polled)succeeded

This is logged as INFO unless the platform comms method is polling, in which case it gets demoted to DEBUG level.

That makes sense for the routine automatic polls on a polled job platform, but manual polls should always be logged as INFO so it's clear what happened as result of the command.

(However, I'm not sure if we can easily distinguish auto and manual polling in the callback, at the moment).