Remove ActionCable leftovers

config/cable.yml

-development:
-  adapter: async
-
-test:
-  adapter: test
-
-production:
-  adapter: redis
-  url: <%= ENV.fetch("REDIS_URL") { "redis://localhost:6379/1" } %>
-  channel_prefix: usermanager_production

test/channels/application_cable/connection_test.rb

-# frozen_string_literal: true
-
-require 'test_helper'
-
-class ApplicationCable::ConnectionTest < ActionCable::Connection::TestCase
-  # test "connects with cookies" do
-  #   cookies.signed[:user_id] = 42
-  #
-  #   connect
-  #
-  #   assert_equal connection.user_id, "42"
-  # end
-end