Refs #30165 -- Removed obsolete doc references to deprecated ugettext() & co.

The u-prefixed variants were removed from the documentation in
6eb4996672ca5ccaba20e468d91a83d1cd019801.

docs/ref/utils.txt

@@ -1027,10 +1027,6 @@ appropriate entities.
 For a complete discussion on the usage of the following see the
 :doc:`translation documentation </topics/i18n/translation>`.
 
-The ``u`` prefix on the functions below comes from a difference in Python 2
-between unicode and bytestrings. If your code doesn't support Python 2, use the
-functions without the ``u``.
-
 .. function:: gettext(message)
 
     Translates ``message`` and returns it as a string.

docs/topics/i18n/translation.txt

@@ -52,12 +52,6 @@ Specify a translation string by using the function
 :func:`~django.utils.translation.gettext`. It's convention to import this
 as a shorter alias, ``_``, to save typing.
 
-.. note::
-    The ``u`` prefixing of ``gettext`` functions was originally to distinguish
-    usage between unicode strings and bytestrings on Python 2. For code that
-    supports only Python 3, they can be used interchangeably. A deprecation for
-    the prefixed functions may happen in a future Django release.
-
 .. note::
     Python's standard library ``gettext`` module installs ``_()`` into the
     global namespace, as an alias for ``gettext()``. In Django, we have chosen