fix: Incorrect status code for missing static files (#29374)

I think the route precedence in Caddy is different when using `handle`
directive, vs when directly using the `error` directive.

This is causing the file `handle {` route, which is a catch-all route is
handling `/static/*` requests that don't have a corresponding file. This
handler however, doesn't respond with 404 status, it responds with 200
status for missing files, and render the `index.html` for our SPA
behaviour.

Now, the CDN we have on release.app.appsmith.com caches responses from
upstream when the status is 200. If it is 404, it won't cache and retry
next time. This is why it's essential that we respond with 404 for files
that don't exist, irrespective of the content of the response.

When the container is starting up, Caddy doesn't have all the
information yet, and may have responded with not-found for one of the
assets. But since this went out with 200 status, our CDN cached it, and
once the file _was_ available with Caddy, the CDN wouldn't retry ever.

This fix will ensure we get 404 status code for requests to `/static/*`
that point to files that don't exist.

deploy/docker/fs/opt/appsmith/caddy-reconfigure.mjs

@@ -84,7 +84,10 @@ parts.push(`
     import file_server
     skip_log
   }
-  error /static/* 404
+
+  handle /static/* {
+    error 404
+  }
 
   handle /info {
     root * /opt/appsmith