Provide regular dumps of Trac database

A long time ago, database dumps of the Trac tables used to be provided for public consumption but that practice has stopped at some point.

I think we should start doing this again (inspired by a discussion I had on Discord with @ulgens today). It would be useful both for people trying to work on code.djangoproject.com locally, but also those who'd like to extract statistics from Trac.

Some of the technical challenges to figure out:

- Where to host the file (it used to be on the wiki, but maybe there's a better place)?
- How to clean the data? The database has things like session ids which should not be shared under any circumstances, as well as user emails which should stay private.