Revert "enable formatting by default"

This reverts PR  #13397 / commit df3248f00a60859ed07f81e87531856b30891396, whilst leaving in place the internal improvements.

IPython/terminal/interactiveshell.py

@@ -200,7 +200,7 b' class TerminalInteractiveShell(InteractiveShell):'
     ).tag(config=True)
 
     autoformatter = Unicode(
-        "black",
+        None,
         help="Autoformatter to reformat Terminal code. Can be `'black'`, `'yapf'` or `None`",
         allow_none=True
     ).tag(config=True)

docs/source/whatsnew/version8.rst

@@ -344,12 +344,11 b' For more information please see the following unit test : ``extensions/tests/tes'
 Auto formatting with black in the CLI
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-If ``black`` is installed in the same environment as IPython, terminal IPython
-will now *by default*  reformat the code in the CLI when possible. You can
-disable this with ``--TerminalInteractiveShell.autoformatter=None``.
-
 This feature was present in 7.x, but disabled by default.
 
+In 8.0, input was automatically reformatted with Black when black was installed.
+This feature has been reverted for the time being.
+You can re-enable it by setting ``TerminalInteractiveShell.autoformatter`` to ``"black"``
 
 History Range Glob feature
 ~~~~~~~~~~~~~~~~~~~~~~~~~~