test: drop autouse gh-106749 heal fixture (ineffective; _bridge.py was the site)

The fixture ran at a different frame depth than the desync and had no
effect on CI. The actual remaining throw site was
StreamingASGITransport.__aexit__, healed in 7cbfd0f.

Author: maxisbey

tests/conftest.py

@@ -1,8 +1,6 @@
 import os
-import sys
-from collections.abc import AsyncIterator, Iterator
+from collections.abc import Iterator
 
-import anyio.lowlevel
 import pytest
 
 # OpenTelemetry's `set_tracer_provider` is set-once per process, so the suite
@@ -25,31 +23,6 @@ def anyio_backend():
     return "asyncio"
 
 
-@pytest.fixture(autouse=True)
-async def _heal_gh106749(anyio_backend: str) -> AsyncIterator[None]:
-    """Re-sync coverage's CTracer after every async test on CPython 3.11.
-
-    CPython gh-106749: anyio delivers a task-group cancel via `coro.throw()`,
-    which on 3.11 skips the outer await chain's `'call'` trace events.
-    coverage.py's CTracer keys its frame stack on those events, so until the
-    next `.send()` resumption, line events are misattributed and dropped. Under
-    xdist a desync at the end of one test carries into the start of the next on
-    the same worker; the missed lines move with worker test ordering.
-
-    `cancel_shielded_checkpoint()` resumes via `.send()`, re-stamping the
-    missing events. The shielded variant is a pure scheduling yield with no
-    cancel delivery, so it cannot perturb a test's cancel-scope nesting. The
-    `anyio_backend` dependency makes anyio's pytest plugin own this fixture so
-    it runs in the test's task; sync tests skip it.
-    """
-    yield
-    # The heal line itself runs while the tracer is desynced (that's the
-    # point), so it cannot record its own execution; on non-3.11 the body is
-    # never entered. Hence lax no cover on the whole tail.
-    if sys.version_info[:2] == (3, 11):  # pragma: lax no cover
-        await anyio.lowlevel.cancel_shielded_checkpoint()
-
-
 @pytest.fixture(name="capfire")
 def _capfire_isolated(capfire: CaptureLogfire) -> Iterator[CaptureLogfire]:
     """Override of logfire's `capfire` that scopes the MCP tracer to the test.