Revert CORS fetch mode for Active Storage

CORS mode doesn't work with redirect-based Active Storage URLs
when the storage bucket uses wildcard Access-Control-Allow-Origin.
Relying on maxEntries alone until specific origin CORS is available.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Gemfile.lock

@@ -13,7 +13,7 @@ GIT
 
 GIT
   remote: https://github.com/hotwired/turbo-rails.git
-  revision: 43bc205155b0eb57e5e016ed0e87a12c29ba2ab2
+  revision: 93ce5bc461cd71af1797e79fcd7e09a19242d080
   branch: offline-cache
   specs:
     turbo-rails (2.0.23)