Migate Faffy (dev server) to Debian 12

[Firefishy]

The OpenStreetMap.org servers now run Debian 12. It is best if we also align the dev server to run Debian 12.

• Announce planned migration to existing dev server users.
• Offline move existing filesystem data to temporary folders.
• Install Debian 12 onto existing partitions without formatting partitions.
• Re-install chef and allow initial setup. May require some package tweaks.
• Move original /home back to correct location.
• Restore postgres databases + reindex.
• Restore mysql databases + reindex.
• Restore user cronjobs.
• Restore encrypted user passwords using chpasswd -e

[Firefishy]

I have BCC emailed all dev server users who have logged in over the last year notifying them about the change. I will email them again when the upgrade has been completed.

I said a likely date for the upgrade is 3rd or 4th September 2024.

[Firefishy]

Some of the reasons for the migration to Debian are captured here: #844

[mmd-osm]

https://master.apis.dev.openstreetmap.org/rails/active_storage/disk/... seems to be unavailable atm (avatar images + gpx traces)

[tomhughes]

That should be fixed now.

[Firefishy]

Thank you for the help @tomhughes