Fix Lint/SymbolConversion cop (#28175)

app/models/concerns/remotable.rb

@@ -5,7 +5,7 @@ module Remotable
 
   class_methods do
     def remotable_attachment(attachment_name, limit, suppress_errors: true, download_on_assign: true, attribute_name: nil)
-      attribute_name ||= "#{attachment_name}_remote_url".to_sym
+      attribute_name ||= :"#{attachment_name}_remote_url"
 
       define_method("download_#{attachment_name}!") do |url = nil|
         url ||= self[attribute_name]

app/models/user_settings/setting.rb

@@ -62,7 +62,7 @@ class UserSettings::Setting
 
   def key
     if namespace
-      "#{namespace}.#{name}".to_sym
+      :"#{namespace}.#{name}"
     else
       name
     end