Comment 12 for bug 2034986

I think we'd want to put it in a "quirk" and those are found in DistUpgradeQuirks.py:

https://git.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/tree/DistUpgrade/DistUpgradeQuirks.py?h=ubuntu/mantic

I think a "StartUpgrade" quirk is likely the best time for this but there should be a check to ensure that we are using the gtk frontend or some other check to ensure that we really need to modify the font.