[python] Removetiledb_ctx references from _soma_tiledb_context.py

[ryan-williams]

Follow-up from #2752. Issue: #1632.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.81%. Comparing base (cde6da1) to head (56946e7).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3341      +/-   ##
==========================================
+ Coverage   85.71%   85.81%   +0.09%     
==========================================
  Files          57       57              
  Lines        6169     6169              
==========================================
+ Hits         5288     5294       +6     
+ Misses        881      875       -6     

Flag	Coverage Δ
python	85.81% <100.00%> (+0.09%)	⬆️

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Components	Coverage Δ
python_api	85.81% <100.00%> (+0.09%)	⬆️
libtiledbsoma	∅ <ø> (∅)

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[nguyenv]

Your documentation corrections are good for how TileDBSOMAContext currently works, but I am doing some refactoring in #3335 which might nullify these changes.