Move "limited federation mode" config to x.mastodon area (#35041)

config/initializers/2_limited_federation_mode.rb

@@ -1,7 +0,0 @@
-# frozen_string_literal: true
-
-Rails.application.configure do
-  config.x.limited_federation_mode = (ENV['LIMITED_FEDERATION_MODE'] || ENV['WHITELIST_MODE']) == 'true'
-
-  warn 'WARN: The environment variable WHITELIST_MODE has been replaced with LIMITED_FEDERATION_MODE, you should rename this environment variable in your configuration.' if ENV.key?('WHITELIST_MODE')
-end

config/initializers/deprecations.rb

@@ -22,3 +22,10 @@ if ENV['MASTODON_USE_LIBVIPS'] == 'false'
     WARNING: Mastodon support for ImageMagick is deprecated and will be removed in future versions. Please consider using libvips instead.
   MESSAGE
 end
+
+if ENV.key?('WHITELIST_MODE')
+  warn(<<~MESSAGE.squish)
+    WARNING: The environment variable WHITELIST_MODE has been replaced with
+    LIMITED_FEDERATION_MODE. Please update your configuration.
+  MESSAGE
+end

config/mastodon.yml

@@ -1,6 +1,7 @@
 ---
 shared:
   experimental_features: <%= ENV.fetch('EXPERIMENTAL_FEATURES', nil) %>
+  limited_federation_mode: <%= (ENV.fetch('LIMITED_FEDERATION_MODE', nil) || ENV.fetch('WHITELIST_MODE', nil)) == 'true' %>
   self_destruct_value: <%= ENV.fetch('SELF_DESTRUCT', nil) %>
   software_update_url: <%= ENV.fetch('UPDATE_CHECK_URL', 'https://api.joinmastodon.org/update-check') %>
   source: