[python] Strip needless wrapper-class docstrings

[johnkerl]

Issue and/or context: As tracked on issue #2407 / [sc-51048].

Note that the intended Python and R API changes are all agreed on and finalized as described in #2407.

Changes:

At present we have four layers:

• User-facing Python like DataFrame
• Wrappers in _tdb_handles.py
• pybind11 as in apis/python/soma_dataframe.cc
• libtiledbsoma as in libtiledbsoma/src/soma/soma_array.h

Throughout the new-shape project (#2407) I've been putting docstrings in the _tdb_handles.py layer which is silly because:

• Users don't read them
• It's double-keystroking on my part to write them (content is the same as in the user-facing layer)

Notes for Reviewer:

This PR is a work in progress. It is not ready for review.

[johnkerl]

This was included in my merge of #3236 into main (inadvertently).