DEV: Disable service worker caching by default (#25723)

Followup to c4559ae575

config/discourse_defaults.conf

@@ -394,4 +394,4 @@ asset_url_salt =
 
 # disable service-worker caching. An 'offline' page will still be used as an offline fallback.
 # This flag is for a temporary experiment, and may be removed at any time
-disable_service_worker_cache = false
+disable_service_worker_cache = true

spec/requests/static_controller_spec.rb

@@ -319,7 +319,7 @@ RSpec.describe StaticController do
       get "/service-worker.js"
       expect(response.status).to eq(200)
       expect(response.content_type).to start_with("application/javascript")
-      expect(response.body).to include("workbox")
+      expect(response.body).to include("addEventListener")
     end
 
     it "replaces sourcemap URL" do