docs: Remove apify-shared from documentation build

[vdusek]

Summary

• Removes apify-shared from the docs build pipeline — it is no longer a dependency of apify-client-python
• Removes cloning of apify-shared-python repo and its docspec dump generation from build_api_reference.sh
• Removes apify_shared references from transformDocs.js (repo URL, version detection, docspec merging)
• Removes apify_shared from the module list in generate_module_shortcuts.py

Test plan

• CI passes

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.60%. Comparing base (7895a4e) to head (4eb2c52).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #639   +/-   ##
=======================================
  Coverage   75.60%   75.60%           
=======================================
  Files          45       45           
  Lines        4271     4271           
=======================================
  Hits         3229     3229           
  Misses       1042     1042           

Flag	Coverage Δ
unit	75.60% <ø> (ø)

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