Revert "ms-obfuscate-issue-email-participant-system-notes into master"

app/graphql/types/notes/note_type.rb

app/models/service_desk_setting.rb

app/models/system_note_metadata.rb

app/presenters/note_presenter.rb

app/serializers/note_entity.rb

app/services/system_notes/issuables_service.rb

doc/api/graphql/reference/index.md

lib/api/entities/note.rb

lib/api/notes.rb

lib/gitlab/email/service_desk/custom_email.rb

lib/gitlab/utils/email.rb

spec/graphql/types/notes/note_type_spec.rb

spec/lib/gitlab/utils/email_spec.rb

spec/presenters/note_presenter_spec.rb

spec/requests/api/graphql/notes/note_spec.rb

spec/requests/api/notes_spec.rb

spec/serializers/note_entity_spec.rb

.../services/issue_email_participants/create_service_spec.rb

...ples/graphql/notes_content_obfuscation_shared_examples.rb