Simplify code involving Globalize.locale

We don't need to set this value. In commit f2ef27d3 I made a mistake
thinking `Globalize.locale` and `I18n.locale` should always be in sync,
but they're actually automatically in sync when `Globalize.locale` is
`nil`.

So the best way to avoid any issues is not to assign `Globalize.locale`,
and use `Globalize.with_locale` where necessary instead.

app/controllers/admin/site_customization/information_texts_controller.rb

@@ -18,12 +18,13 @@ class Admin::SiteCustomization::InformationTextsController < Admin::SiteCustomiz
             next
           else
             text = I18nContent.find_or_create_by!(key: content[:id])
-            Globalize.locale = locale
+            Globalize.with_locale(locale) do
               text.update!(value: value)
             end
           end
         end
       end
+    end
 
     redirect_to admin_site_customization_information_texts_path,
                 notice: t("flash.actions.update.translation")

app/controllers/application_controller.rb

@@ -55,7 +55,6 @@ class ApplicationController < ActionController::Base
       end
 
       I18n.locale = locale
-      Globalize.locale = I18n.locale
     end
 
     def set_layout

app/controllers/management/base_controller.rb

@@ -46,7 +46,6 @@ class Management::BaseController < ActionController::Base
       session[:locale] ||= I18n.default_locale
 
       I18n.locale = session[:locale]
-      Globalize.locale = I18n.locale
     end
 
     def current_budget

spec/spec_helper.rb

@@ -26,7 +26,6 @@ RSpec.configure do |config|
 
   config.before do |example|
     I18n.locale = :en
-    Globalize.locale = nil
     Globalize.set_fallbacks_to_all_available_locales
     Setting["feature.user.skip_verification"] = nil
   end