Use cloud.zed.dev for install.sh (#42399)

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.

script/get-released-version

@@ -18,4 +18,4 @@ case $channel in
     ;;
 esac
 
-curl -s "https://zed.dev/api/releases/latest?asset=zed&os=macos&arch=aarch64$query" | jq -r .version
+curl -s "https://cloud.zed.dev/releases/$channel/latest/asset?asset=zed&os=macos&arch=aarch64" | jq -r .version