Remove instance variables from helper usage (#24203)

.rubocop_todo.yml

app/controllers/application_controller.rb

app/helpers/application_helper.rb

app/helpers/instance_helper.rb

app/helpers/jsonld_helper.rb

app/lib/activitypub/activity/create.rb

app/lib/activitypub/activity/delete.rb

app/lib/activitypub/activity/flag.rb

app/lib/activitypub/activity/update.rb

app/lib/activitypub/dereferencer.rb

...services/activitypub/fetch_featured_collection_service.rb

...ces/activitypub/fetch_featured_tags_collection_service.rb

app/services/activitypub/fetch_replies_service.rb

.../activitypub/prepare_followers_synchronization_service.rb

app/services/activitypub/synchronize_followers_service.rb

app/views/auth/registrations/new.html.haml

app/views/auth/registrations/rules.html.haml

spec/controllers/shares_controller_spec.rb

spec/helpers/application_helper_spec.rb