Remove unused translations

The migration for the ToS signup field happend in 2014. Everyone who hasn't updated yet needs to live with the English text "Terms of Service". There's no need to keep these unused translations forever.

config/locales/server.en.yml

@@ -3496,10 +3496,6 @@ en:
       ## [Welcome to %{title}](#welcome)
       An account is required. Please ask an existing member for an invite or log in to continue.
 
-  terms_of_service:
-    title: "Terms of Service"
-    signup_form_message: 'I have read and accept the <a href="%{base_path}/tos" target="_blank">Terms of Service</a>.'
-
   deleted: "deleted"
 
   image: "image"

db/migrate/20140929204155_migrate_tos_setting.rb

@@ -4,11 +4,7 @@ class MigrateTosSetting < ActiveRecord::Migration[4.2]
   def up
     res = execute("SELECT * FROM site_settings WHERE name = 'tos_accept_required' AND value = 't'")
     if res.present? && res.cmd_tuples > 0
-      label = nil
-
-      I18n.overrides_disabled do
-        label = I18n.t("terms_of_service.signup_form_message", base_path: "")
-      end
+      label = 'Terms of Service'
 
       res = execute("SELECT value FROM site_texts WHERE text_type = 'tos_signup_form_message'")
       if res.present? && res.cmd_tuples == 1

db/migrate/20141014191645_fix_tos_name.rb

@@ -2,9 +2,10 @@
 
 class FixTosName < ActiveRecord::Migration[4.2]
   def up
-    I18n.overrides_disabled do
-      execute DB.sql_fragment('UPDATE user_fields SET name = ? WHERE name = ?', I18n.t('terms_of_service.title'), I18n.t("terms_of_service.signup_form_message", base_path: ""))
-    end
-
+    execute <<~SQL
+      UPDATE user_fields
+      SET name = 'Terms of Service'
+      WHERE name = 'I have read and accept the <a href="/tos" target="_blank">Terms of Service</a>.'
+    SQL
   end
 end