Similar to #42246, we'd like to avoid having Vercel on the critical
path.

https://zed.dev/install.sh is served from Cloudflare by intercepting a
route on that page, so this makes the shell-based install flow vercel independent.

Release Notes:

- `./script/install.sh` will now fetch assets via
`https://cloud.zed.dev/`
instead of `https://zed.dev`. As before it will redirect to GitHub
releases
  to complete the download.