ref: Remove _ai_pipeline_name context variable

[alexander-alderman-webb]

Description

The set_ai_pipeline_name() function is not used anywhere in the SDK.

Issues

Reminders

• Please add tests to validate your changes, and lint your code using uv run ruff.
• Add GH Issue ID & Linear ID (if applicable)
• PR title should use conventional commit style (feat:, fix:, ref:, meta:)
• For external contributors: CONTRIBUTING.md, Sentry SDK development docs, Discord community

[github-actions]

Codecov Results 📊

✅ 69679 passed | ⏭️ 3315 skipped | Total: 72994 | Pass Rate: 95.46% | Execution Time: 213m 32s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📉 -65972
Passed Tests	📉 -62156
Failed Tests	—
Skipped Tests	📉 -3816

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 2302 uncovered lines.
❌ Project coverage is 89.8%. Comparing base (e9b6185) to head (e6995f4).

Coverage diff

@@            Coverage Diff             @@
##        master       #PR       +/-##
==========================================
- Coverage    90.18%    89.80%    -0.38%
==========================================
  Files          193       185        -8
  Lines        25790     22560     -3230
  Branches      9532      8166     -1366
==========================================
+ Hits         23256     20258     -2998
- Misses        2534      2302      -232
- Partials      1434      1322      -112

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