chore: remove Python UPF examples and related documentation

[germa89]

Description

As the title.

Issue linked

Close #4175

Checklist

• I have visited and read Develop PyMAPDL.
• I have tested my changes locally
• I have added necessary documentation or updated existing documentation.
• I have followed the PyMAPDL coding style guidelines.
• I have added appropriate unit tests that also ensure the minimal coverage criteria.
• I have reviewed my changes before submitting this pull request.
• I have linked the issue or issues that are solved to the PR if any.
• I have assigned this PR to myself.
• I have marked this PR as draft if it is not ready to be reviewed yet.
• I have made sure that the title of my PR follows Commit naming conventions (e.g. feat: adding new MAPDL command)

[Copilot]

Pull Request Overview

This PR removes Python UPF (User Programmable Features) examples and documentation from PyMAPDL, addressing issue #4175. The removal includes comprehensive cleanup of UPF-related content across documentation files and example directories.

• Removes the entire UPF user guide documentation and Python UPF examples
• Updates the main user guide to clarify that UPF commands are not supported in PyMAPDL
• Removes references to UPF content from table of contents and index files

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
doc/source/user_guide/upf.rst	Complete removal of the Python UPF user guide documentation
doc/source/user_guide/mapdl.rst	Adds clarification that UPF commands are not supported in PyMAPDL
doc/source/user_guide/index.rst	Removes UPF from the advanced topics table of contents
doc/source/examples/extended_examples/index.rst	Removes Python UPF examples from the extended examples index
doc/source/examples/extended_examples/Python_UPF/python_upf_examples.rst	Complete removal of Python UPF example documentation

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.38%. Comparing base (ec3cb1d) to head (7bff95a).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4197      +/-   ##
==========================================
+ Coverage   91.31%   91.38%   +0.07%     
==========================================
  Files         193      193              
  Lines       15731    15731              
==========================================
+ Hits        14364    14376      +12     
+ Misses       1367     1355      -12     

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[germa89]

@pyansys-ci-bot LGTM.

[pyansys-ci-bot]

✅ Approving this PR because germa89 said so in here 😬