Clean unnecessary 'attachToDocument' in 'spec/frontend/notes'

Summary

As described in &2419 (closed), we need to clean up our Jest tests from unnecessary attachToDocument usage

Risks

No risks

Involved specs

• spec/frontend/notes/components/comment_form_spec.js
• spec/frontend/notes/components/discussion_jump_to_next_button_spec.js
• spec/frontend/notes/components/discussion_notes_spec.js
• spec/frontend/notes/components/note_app_spec.js
• spec/frontend/notes/components/note_edited_text_spec.js