Add and apply Style/BlockDelimiters rubocop rule

We were already using it most of the time, but there were a few places
were we used brackets for multiline blocks.

app/controllers/remote_translations_controller.rb

@@ -20,11 +20,9 @@ class RemoteTranslationsController < ApplicationController
     def set_remote_translations
       remote_translations = remote_translations_params["remote_translations"]
       decoded_remote_translations = ActiveSupport::JSON.decode(remote_translations)
-      @remote_translations = decoded_remote_translations.map { |remote_translation|
-                              remote_translation.slice("remote_translatable_id",
-                                                       "remote_translatable_type",
-                                                       "locale")
-                            }
+      @remote_translations = decoded_remote_translations.map do |remote_translation|
+        remote_translation.slice("remote_translatable_id", "remote_translatable_type", "locale")
+      end
     end
 
     def translations_enqueued?(remote_translation)