docs: remove not changed sections in upgrade_417

Author: kenjis

user_guide_src/source/installation/upgrade_417.rst

@@ -16,36 +16,3 @@ Breaking Changes
 ****************
 
 - ``get_cookie()`` when ``$xssClean`` is true changed the output. Now it uses ``FILTER_SANITIZE_FULL_SPECIAL_CHARS``, not ``FILTER_SANITIZE_STRING``. Make sure the change is acceptable or not. Note that using XSS filtering is a bad practice. It does not prevent XSS attacks perfectly. Using ``esc()`` with the correct ``$context`` in the views is recommended.
-
-Breaking Enhancements
-*********************
-
-none.
-
-Project Files
-*************
-
-Numerous files in the **project space** (root, app, public, writable) received updates. Due to
-these files being outside of the **system** scope they will not be changed without your intervention.
-There are some third-party CodeIgniter modules available to assist with merging changes to
-the project space: `Explore on Packagist <https://packagist.org/explore/?query=codeigniter4%20updates>`_.
-
-.. note:: Except in very rare cases for bug fixes, no changes made to files for the project space
-    will break your application. All changes noted here are optional until the next major version,
-    and any mandatory changes will be covered in the sections above.
-
-Content Changes
-===============
-
-The following files received significant changes (including deprecations or visual adjustments)
-and it is recommended that you merge the updated versions with your application:
-
-*
-
-All Changes
-===========
-
-This is a list of all files in the **project space** that received changes;
-many will be simple comments or formatting that have no effect on the runtime:
-
-*