Remove the soap code

[adiroiban]

          Thanks for the feedback.

I think that is safe to just remove the SOAP code

It is already broken.

It looks like we still have code that was not ported to py3 ... or for which we don't execute the tests.

If anyone want to have SOAP support in Twisted, they can send a PR

$ pip install soappy
$ python
Python 3.12.2 (main, Feb 25 2024, 16:35:05) [GCC 11.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from twisted.web.soap import SOAPPublisher
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/adi/chevah/twisted/src/twisted/web/soap.py", line 19, in <module>
    import SOAPpy
  File "/home/adi/chevah/twisted/venv-3.12/lib/python3.12/site-packages/SOAPpy/__init__.py", line 3, in <module>
    from version import __version__
ModuleNotFoundError: No module named 'version'
>>> 

Originally posted by @adiroiban in #12145 (comment)