Merge branch 'rails5-boolean-cast' into 'master'

Fix boolean casting for nil value

Closes #46925

See merge request gitlab-org/gitlab-ce!19202

app/models/service.rb

@@ -206,10 +206,11 @@ class Service < ActiveRecord::Base
     args.each do |arg|
       class_eval %{
         def #{arg}?
+          # '!!' is used because nil or empty string is converted to nil
           if Gitlab.rails5?
-            !ActiveModel::Type::Boolean::FALSE_VALUES.include?(#{arg})
+            !!ActiveRecord::Type::Boolean.new.cast(#{arg})
           else
-            ActiveRecord::ConnectionAdapters::Column::TRUE_VALUES.include?(#{arg})
+            !!ActiveRecord::Type::Boolean.new.type_cast_from_database(#{arg})
           end
         end
       }