fix(starlette): Set transaction name on current scope in sync handler

[mjq]

The sync request/response handler passed the isolation scope to _set_transaction_name_and_source, but the transaction/segment span lives on the current scope. As a result the route-resolved name never reached the span for sync endpoints, which were instead named by the raw URL from the ASGI middleware (transaction_info.source of url rather than route). Async handlers already used the current scope and were unaffected.

Pass the current scope (already computed above) so sync and async handlers behave identically:

• streaming: the segment name / sentry.segment.name.source are route-based
• static: the transaction event name / source are route-based

For parametrized routes this also removes high-cardinality URL transaction names for sync endpoints.

Found while working on #7183.

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Codecov Results 📊

✅ 117639 passed | ⏭️ 6732 skipped | Total: 124371 | Pass Rate: 94.59% | Execution Time: 423m 38s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📈 +4448
Passed Tests	📈 +4482
Failed Tests	📉 -1
Skipped Tests	📉 -33

➖ Removed Tests (1)

View removed tests

• test_span_streaming_quart_auth_user_id[42-True]
  • File: tests.integrations.quart.test_quart

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 2488 uncovered lines.
❌ Project coverage is 90.22%. Comparing base (base) to head (head).

Coverage diff

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  Files          193       193         —
  Lines        25433     25433         —
  Branches      9346      9346         —
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+ Hits         22952     22945        -7
- Misses        2481      2488        +7
- Partials      1436      1436         —

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[ericapisani]

Great catch, and thanks for making these changes. Very minor suggestion for the span streaming test, but at the core this LGTM.

Thanks for also separating span streaming enabled and the transactions approach into 2 separate tests - will make it easier when we remove the transactions code 🔥