[ticket/13280] Proper patch for the use of the symfony_request class

In this PR I do a few things:
1. I revert the previous PR
2. I fix the tests so now they are failing without this patch as expected
3. I don't escape the globals when creating the symfony_request object (so the class always returns non ecaped data)
4. I track the uses of the symfony_request object in the core and I escape the output when it is necessary
5. I add a warning in the class header block and in the services.yml file to say that this class does not escape the input.

By the way there is a small change in phpbb_mock_controller_helper so the tests of some extensions (ie. \phpbb\pages\tests\event\event_listener_base and \phpbb\pages\tests\event\show_page_links_test for the pages extension @VSE) will fail.
Could've kept this on one line instead of introducing another variable.