Slightly reduce RAM usage (#7301)

* No need to re-require sidekiq plugins, they are required via Gemfile

* Add derailed_benchmarks tool, no need to require TTY gems in Gemfile

* Replace ruby-oembed with FetchOEmbedService

Reduce startup by 45382 allocated objects

* Remove preloaded JSON-LD in favour of caching HTTP responses

Reduce boot RAM by about 6 MiB

* Fix tests

* Fix test suite by stubbing out JSON-LD contexts

app/controllers/api/web/embeds_controller.rb

@@ -9,9 +9,12 @@ class Api::Web::EmbedsController < Api::Web::BaseController
     status = StatusFinder.new(params[:url]).status
     render json: status, serializer: OEmbedSerializer, width: 400
   rescue ActiveRecord::RecordNotFound
-    oembed = OEmbed::Providers.get(params[:url])
-    render json: Oj.dump(oembed.fields)
-  rescue OEmbed::NotFound
-    render json: {}, status: :not_found
+    oembed = FetchOEmbedService.new.call(params[:url])
+
+    if oembed
+      render json: oembed
+    else
+      render json: {}, status: :not_found
+    end
   end
 end