chore: Wait for turbo in picture-descriptions feature spec

This spec is still flaky and we now try to wait for turbo do
not be busy anymore to be sure the page has updated.

Author: tvdeyen

spec/features/admin/picture_library_integration_spec.rb

@@ -239,8 +239,10 @@
       end
 
       select(language.name, from: "Language")
+      expect(page).to have_no_css("turbo-frame#picture_descriptions[busy]")
       expect(page).to have_field("Description", with: "This is an amazing image.")
       select(german.name, from: "Language")
+      expect(page).to have_no_css("turbo-frame#picture_descriptions[busy]")
       expect(page).to have_field("Description", with: "Tolles Bild.")
     end
   end