remove unused buildkite pipeline

[richvdh]

the buildkite build is archived

Preview: https://pr1098--matrix-org-previews.netlify.app

[afranke]

Overall this looks fine.
My main concern is that relying on docker images is not very idiomatic in the GHA world, and the same could be achieved using actions. Now that we figured how to cache things, we can use that for the gatsby node_modules and the custom image becomes moot.

I see advantages to the actions approach:

• The images are basically unmaintained currently. Their sole purpose is this pipeline, so we’re the only ones using them and we hardly ever update them, with all the risks that it has.
• Actions within the pipeline definition are more transparent than “stuff done outside”.
• I have a hunch that there’s an overhead to the current image-based approach, but I don’t have scientific evidence to back it.

Does that make sense?

I don’t mean to put an additional burden on you and I volunteer to write the actions version if you think it’s worth pursuing, unless you want to tackle it yourself.

I also acknowledge the argument that we could merge this now and worry about improving upon it later, and we can do it if you think that’s the way to go. It feels a bit futile to move files just to remove them afterwards though.

[richvdh]

I agree that having essentially unmaintained images is risky, and if you'd like to investigate better solutions, that sounds great to me.

Still, I'd rather merge this in the meantime than have unused things in the repo, which will be confusing for everyone.