Do not spam logs when repeated log lines are found, as they are not that important to us

Sometimes the same log line is produced and put in multiple files (e.g. mail.log and mail.warn), so we can safely ignore them.

Other times, the same log line is produced multiple times in the same second, and I believe it's safe to continue ignoring them, as the same payload spaning over one second will generate a slightly different line (different time).

Supporting ingesting multiple lines exact with same content is too much work and not worth for the time being.