Remove framework.trusted_proxies option

As deprecated in symfony/symfony#21830 and symfony/symfony#22238 (BC break)

Author: ogizanagi

symfony/framework-bundle/3.3/etc/packages/framework.yaml

@@ -4,7 +4,6 @@ framework:
     #csrf_protection: null
     #http_method_override: true
     #trusted_hosts: null
-    #trusted_proxies: null
     # https://symfony.com/doc/current/reference/configuration/framework.html#handler-id
     #session:
     #    handler_id: session.handler.native_file