feat(batcher): Add hard span limit

[alexander-alderman-webb]

Description

Add a hard span limit after which new spans are not added to the batcher. This mirrors the per-bucket logic.

This aims to keep memory use bounded at a multiple of the size of live StreamedSpan objects.

Adapt the test_drop_after_max_reached() test which tests the per-bucket span limit to a test which tests the global span limit. Also add the test_capture_after_flush_with_global_limit() to ensure accurate bookkeeping to track the number of spans in the batcher.

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 📊

✅ 101547 passed | ⏭️ 6635 skipped | Total: 108182 | Pass Rate: 93.87% | Execution Time: 353m 45s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📈 +30
Passed Tests	📈 +30
Failed Tests	—
Skipped Tests	—

All tests are passing successfully.

✅ Patch coverage is 83.33%. Project has 2498 uncovered lines.
❌ Project coverage is 90.01%. Comparing base (base) to head (head).

Files with missing lines (1)

File	Patch %	Lines
sentry_sdk/_span_batcher.py	83.33%	⚠️ 1 Missing

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
- Coverage    90.02%    90.01%    -0.01%
==========================================
  Files          193       193         —
  Lines        25010     25014        +4
  Branches      9032      9032         —
==========================================
+ Hits         22514     22516        +2
- Misses        2496      2498        +2
- Partials      1434      1435        +1

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