tests: Add span streaming tests (13)

[sentrivana]

Description

Span first on master is finally in a state where we can add meaningful tests.

Longer term, we obviously want to run the whole existing test suite on span first, but this will have to do for now.

Issues

Reminders

• Please add tests to validate your changes, and lint your code using tox -e linters.
• 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]

Semver Impact of This PR

🟢 Patch (bug fixes)

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[github-actions]

Codecov Results 📊

✅ 6 passed | ⏭️ 1 skipped | Total: 7 | Pass Rate: 85.71% | Execution Time: 3.23s

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 14886 uncovered lines.

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Generated by Codecov Action

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