Limit the number of Trackback and Referral Links stored in Confluence

Trackback links and referral links can currently be added to a page eternally. It seems useless to have such an ever-growing list, and when the list gets too long, displaying it on the info page is in nobody's interests.

While confluence.atlassian.com no longer actually displays referral links, it still records them (at time of writing and not long after). There is a page with over 40000 referral links recorded against it. While this data may be interesting to analyse, there is no chance that displaying it all on the info page would be worthwhile, and even recording it (and exporting it) does not help the performance of the system.

I suggest fixing this by adding a configurable limit to the number of trackbacks and referrals recorded against each page.
It would be nice to also allow new links to replace old ones. However I've noticed that the ratio of genuine trackbacks vs trackback spam deteriorates over time, so old, stale trackbacks are probably still better than fresh spam trackbacks.