Rename AvailableLocales.available_locales method

I'm not sure whether we should rename the class instead. I'm renaming
the method because renaming the class would require more changes.

spec/shared/system/remotely_translatable.rb

@@ -11,7 +11,7 @@ shared_examples "remotely_translatable" do |factory_name, path_name, path_argume
     Setting["feature.remote_translations"] = true
     available_locales_response = %w[de en es fr pt zh-Hans]
     expect(RemoteTranslations::Microsoft::AvailableLocales)
-      .to receive(:available_locales).at_most(4).times
+      .to receive(:locales).at_most(4).times
       .and_return(available_locales_response)
     allow(Rails.application.secrets).to receive(:microsoft_api_key).and_return("123")
   end