[flutter_tools] Prevent web ServiceWorker from modifying fetch requests. (#50312)

packages/flutter_tools/lib/src/build_system/targets/web.dart

@@ -358,9 +358,7 @@ self.addEventListener('fetch', function (event) {
         if (response) {
           return response;
         }
-        return fetch(event.request, {
-          credentials: 'include'
-        });
+        return fetch(event.request);
       })
   );
 });