FIX: use allowlist and blocklist terminology (#10209)

This is a PR of the renaming whitelist to allowlist and blacklist to the blocklist.

spec/serializers/user_serializer_spec.rb

@@ -259,7 +259,7 @@ describe UserSerializer do
     context "with user custom field" do
       before do
         plugin = Plugin::Instance.new
-        plugin.whitelist_public_user_custom_field :public_field
+        plugin.allow_public_user_custom_field :public_field
       end
 
       after do