Replace remaining references to `Note.create_cross_reference_note`

app/models/concerns/mentionable.rb

app/models/note.rb

app/services/git_push_service.rb

app/services/notes/create_service.rb

app/services/notes/update_service.rb

spec/models/concerns/mentionable_spec.rb

spec/services/git_push_service_spec.rb

spec/services/notification_service_spec.rb

spec/support/mentionable_shared_examples.rb