fix(tracing): Stop setting NoOpSpan on scope in the streaming trace lifecycle

[alexander-alderman-webb]

Description

Do not set a transaction-based span on the scope when span streaming. The early returns in start_span() and start_transaction() are not sufficient as they return NoOpSpan when span streaming, and NoOpSpan still mutates scopes on __enter__() and __exit__().

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 📊

✅ 92197 passed | ⏭️ 6304 skipped | Total: 98501 | Pass Rate: 93.6% | Execution Time: 311m 25s

📊 Comparison with Base Branch

Metric	Change
Total Tests	—
Passed Tests	—
Failed Tests	—
Skipped Tests	—

✨ No test changes detected

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 2478 uncovered lines.
✅ Project coverage is 89.69%. Comparing base (base) to head (head).

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
+ Coverage    89.69%    89.69%        —%
==========================================
  Files          193       193         —
  Lines        24033     24039        +6
  Branches      8350      8354        +4
==========================================
+ Hits         21555     21561        +6
- Misses        2478      2478         —
- Partials      1387      1387         —

---

Generated by Codecov Action