DEV: Merge package.json files (#21172)

This means: a single yarn.lock and removing one of the package.json files

spec/lib/discourse_js_processor_spec.rb

@@ -151,11 +151,7 @@ RSpec.describe DiscourseJsProcessor do
 
     let(:mini_racer) do
       ctx = MiniRacer::Context.new
-      ctx.eval(
-        File.open(
-          "#{Rails.root}/app/assets/javascripts/node_modules/handlebars/dist/handlebars.js",
-        ).read,
-      )
+      ctx.eval(File.open("#{Rails.root}/node_modules/handlebars/dist/handlebars.js").read)
       ctx.eval(helpers)
       ctx
     end