Replace a class in forum-list.html.twig to mach naming convention

If this change is going to happen, it should also happen with the other themes doing this: Olivero and Umami

I'd like to suggest changing this to "won't fix" If this landed when the issue was created in 2015 (Drupal 8 was still in beta) I'd be all for it. ~7 years in, the risks of disrupting an existing site with the classname change (however unlikely) still seems to outweigh the benefits of changing the class name many years later.

@bnjmnm could this almost be a policy that we should avoid adding new classes to core templates? Will post to #frontend to get a theme API maintainer thought.

I don't think this is actually a theme system issue so moving to the other component. I agree that benefits of the change would be minimal. Regardless of that, to me, it seems fine to fix this in the product themes (Claro, Olivero, and Umami). It's allowed by the BC policies of these themes. Also, based on the contrib search, it doesn't seem like this would break anything in contrib.

could this almost be a policy that we should avoid adding new classes to core templates

We do want the flexiblity to change stuff in the product themes. Starterkit (and Stable/Stable9) exist to provide markup predictability for sites that need it so we have freedom in Claro/Olivero/etc. My reservations are specific to this specific use case because I'm not convinced there's any noticeable benefit to making such a change in 2023, yet there's a slight chance this being an unwelcome disruption to someone.

But ultimately, if another committer and/or FEFM thinks it fine and this lands, I'm fine with it. While it's true I'm expressing an opinion regarding where this issue goes, that opinion is positioned much closer to indifference than it is "strongly agree"

This now belongs if the Forum contrib module.