Revert "PERF: Move highlightjs to a background worker, and add result cache (#10191)"

This caused a CORS error when used with S3 asset storage

This reverts commit d09f283e911c0847ca23372aceefc344526690d2.

lib/discourse_js_processor.rb

@@ -56,7 +56,6 @@ class DiscourseJsProcessor
       activate-account
       auto-redirect
       embed-application
-      highlightjs-worker
       app-boot
     ).any? { |f| relative_path == "#{js_root}/#{f}.js" }