Enable RSpec/NotToNot cop and auto-correct offenses

.rubocop.yml

doc/development/testing.md

features/steps/admin/users.rb

features/steps/dashboard/todos.rb

features/steps/project/commits/commits.rb

features/steps/project/issues/award_emoji.rb

features/steps/project/issues/issues.rb

features/steps/project/merge_requests.rb

features/steps/shared/note.rb

spec/controllers/admin/projects_controller_spec.rb

spec/controllers/projects/compare_controller_spec.rb

spec/controllers/projects/group_links_controller_spec.rb

spec/controllers/projects/issues_controller_spec.rb

spec/controllers/projects/project_members_controller_spec.rb

spec/controllers/registrations_controller_spec.rb

spec/controllers/sessions_controller_spec.rb

spec/factories_spec.rb

spec/features/admin/admin_runners_spec.rb

spec/features/admin/admin_users_spec.rb

spec/features/builds_spec.rb