chore(pydantic-ai): Remove transaction-based tracing

[alexander-alderman-webb]

Description

Remove branches for the static trace lifecycle.
Also remove manual tracing API calls in tests, as the outer transaction is no longer needed.

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 📊

✅ 87783 passed | ❌ 2 failed | ⏭️ 4112 skipped | Total: 91897 | Pass Rate: 95.52% | Execution Time: 285m 59s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📉 -45809
Passed Tests	📉 -42813
Failed Tests	📈 +2
Skipped Tests	📉 -2998

➕ New Tests (2)

View new tests

• test_cache_spans_item_size
  • File: tests.integrations.django.test_cache_module
  • Status: ❌ Failing
• test_cache_spans_templatetag
  • File: tests.integrations.django.test_cache_module
  • Status: ❌ Failing

❌ Failed Tests

test_cache_spans_item_size

File: tests.integrations.django.test_cache_module
Suite: py3.12-django-v4.2.30
Error: tests/integrations/django/test_cache_module.py:526: in test_cache_spans_item_size assert not spans[0]["attributes"]["cache.hit"] E assert not True

Stack Trace

tests/integrations/django/test_cache_module.py:526: in test_cache_spans_item_size
    assert not spans[0]["attributes"]["cache.hit"]
E   assert not True

test_cache_spans_templatetag

File: tests.integrations.django.test_cache_module
Suite: py3.13-django-v6.1
Error: tests/integrations/django/test_cache_module.py:338: in test_cache_spans_templatetag assert not spans[0]["attributes"]["cache.hit"] E assert not True

Stack Trace

tests/integrations/django/test_cache_module.py:338: in test_cache_spans_templatetag
    assert not spans[0]["attributes"]["cache.hit"]
E   assert not True

✅ Patch coverage is 100.00%. Project has 2276 uncovered lines.
✅ Project coverage is 90.27%. Comparing base (c3c44b1) to head (205ea12).

Coverage diff

@@            Coverage Diff             @@
##        master       #PR       +/-##
==========================================
+ Coverage    90.24%    90.27%    +0.03%
==========================================
  Files          193       185        -8
  Lines        25724     23399     -2325
  Branches      9504      8572      -932
==========================================
+ Hits         23214     21123     -2091
- Misses        2510      2276      -234
- Partials      1435      1361       -74

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