Revert "merged branch Tobion/flattenexception (PR #9111)"

This reverts commit 53b2048c4cf0b62251de3906c4665ff5adf31ec4, reversing
changes made to c60a8e962b03b6476db70c962a839b98127b1743.
Merge branch '2.3'

* 2.3:
  Fix: duplicate usage of Symfony\Component\HttpFoundation\Response
  [Form] add support for Length and Range constraint in order to replace MaxLength, MinLength, Max and Min constraints in next release (2.3)
  Revert "merged branch Tobion/flattenexception (PR #9111)"
  [Form] check the required output timezone against the actual timezone of the input datetime object, rather than the expected timezone supplied

Conflicts:
	src/Symfony/Component/HttpKernel/EventListener/ExceptionListener.php