[SE-370] Avoid logging every minute the PRs list from GitHub, to reduce log size in DB
INFO messages are being logged to DB, and because pr_watch
runs every minute, the DB is getting filled with responses that come from GitHub, each one can be around 15 Kb; this is making the logs take a lot of space and thus the backups too. This PR makes the responses not be logged to DB.
We still log the queries we do to GitHub (small line).