Cleanup: remove "<pep8 compliant>" from headers

It can be assumed that all scripts comply with basic pep8 formatting
regarding white-space, indentation etc.

Also remove note in best practices page & update `tests/python/pep8.py`.

If we want to exclude some scripts from make format,
this can be done by adding them to `ignore_files` in:
source/tools/utils_maintenance/autopep8_format_paths.py

Or using `# nopep8` for to ignore for individual lines.

Ref T98554

doc/python_api/rst/info_best_practice.rst

@@ -40,15 +40,6 @@ As well as pep8 we have additional conventions used for Blender Python scripts:
 - pep8 also defines that lines should not exceed 79 characters,
   we have decided that this is too restrictive so it is optional per script.
 
-Periodically we run checks for pep8 compliance on Blender scripts,
-for scripts to be included in this check add this line as a comment at the top of the script:
-
-``# <pep8 compliant>``
-
-To enable line length checks use this instead:
-
-``# <pep8-80 compliant>``
-
 
 User Interface Layout
 =====================