Stop fontconfig from loading from host’s /etc/fonts/conf.d

[gunnarhj]

Fixes: https://launchpad.net/bugs/2025651

At the moment the snaps in at least lunar and mantic load font configuration both from gnome-42-2204 and from the host system’s /etc/fonts/conf.d. This has proved to confuse fontconfig and result in unexpected issues. Stopping the snaps from loading from /etc/fonts/conf.d seems to fix the issue.

This PR reverts part of canonical/snapcraft@407dc755, which is sad IMO. But it’s a result of the reluctance to use font configuration from the host system as expressed in this comment, and for now the proposed change is the easiest way to stop fontconfig from being confused.

[seb128]

Thanks, as mentioned on canonical/snapcraft#4257 that's probably the right thing to do.

One extra note, I wonder if we should add a comment explaining that etc isn't not included and why, perhaps simply pointed to https://bugs.launchpad.net/bugs/2025651 ?

The rational would be to have things less confusing for the next person trying to figure out how things are working (which could be well be us in the future trying to remember why things are set up the way they are)

[gunnarhj]

I wonder if we should add a comment explaining that etc isn't not included and why, perhaps simply pointed to https://bugs.launchpad.net/bugs/2025651 ?

Good idea. I added such a comment.