Check request finishes in remote translations spec

That way we make sure the request is finished before the test finishes.
We were getting a failure in GitHub Actions because an unrelated test
executed after this one had its locale set to Spanish (just for one
test, though), and one possible explanation could be that a previous
request which changed I18n.locale was still being executed.

spec/shared/system/remotely_translatable.rb

@@ -205,6 +205,7 @@ shared_examples "remotely_translatable" do |factory_name, path_name, path_argume
 
         click_button "Traducir página"
 
+        expect(page).not_to have_button "Traducir página"
         expect(RemoteTranslation.count).to eq(0)
         expect(resource.translations.count).to eq(2)
       end