feat(asyncpg): Add span streaming support

[ericapisani]

Migrates the asyncpg integration to support the stream trace lifecycle.

The integration now uses record_sql_queries_supporting_streaming and StreamedSpan so that DB spans are emitted as soon as they complete rather than being buffered until transaction end.

Tests are parameterized over both span_streaming=True and span_streaming=False to verify both paths.

Fixes PY-2305, fixes #6003

[linear-code]

PY-2305 Migrate asyncpg to span first

[ericapisani]

bugbot run

[ericapisani]

@sentry review

[github-actions]

Codecov Results 📊

✅ 13 passed | Total: 13 | Pass Rate: 100% | Execution Time: 9.83s

📊 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 8.16%. Project has 15073 uncovered lines.
❌ Project coverage is 31.33%. Comparing base (base) to head (head).

Files with missing lines (1)

File	Patch %	Lines
asyncpg.py	10.87%	⚠️ 123 Missing

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
- Coverage    31.35%    31.33%    -0.02%
==========================================
  Files          190       190         —
  Lines        21930     21950       +20
  Branches      7382      7390        +8
==========================================
+ Hits          6876      6877        +1
- Misses       15054     15073       +19
- Partials       581       581         —

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[ericapisani]

@sentrivana I realize this code hasn't been touched in 2 years, but since you were the last author - I'm wondering if you can recall why this is sitting outside the record_sql_queries context manager - this looks like it should be sitting within it.