Revert "DEV: Migrate existing cookies to Rails 7 format"

This reverts commit 66e8fe9cc6 as it
unexpectedly caused some users to be logged out. We are investigating
the problem.

config/application.rb

@@ -171,9 +171,6 @@ module Discourse
     require "middleware/discourse_public_exceptions"
     config.exceptions_app = Middleware::DiscoursePublicExceptions.new(Rails.public_path)
 
-    require "middleware/cookies_rotator"
-    config.middleware.insert_before ActionDispatch::Cookies, Middleware::CookiesRotator
-
     require "discourse_js_processor"
     require "discourse_sourcemapping_url_processor"
 

config/initializers/new_framework_defaults_7_0.rb

@@ -25,7 +25,7 @@ Rails.application.config.action_view.apply_stylesheet_media_default = false
 #
 # See upgrading guide for more information on how to build a rotator.
 # https://guides.rubyonrails.org/v7.0/upgrading_ruby_on_rails.html
-Rails.application.config.active_support.key_generator_hash_digest_class = OpenSSL::Digest::SHA256
+# Rails.application.config.active_support.key_generator_hash_digest_class = OpenSSL::Digest::SHA256
 
 # Change the digest class for ActiveSupport::Digest.
 # Changing this default means that for example Etags change and