Fixture to catch leaked threads (DI-1008)

pytest.log

$ pytest tests/snuba/api/endpoints/test_organization_trace_meta.py::OrganizationEventsTraceMetaEndpointTest::test_bad_ids -vvvv
=============================== test session starts ================================
platform darwin -- Python 3.13.1, pytest-8.1.2, pluggy-1.5.0 -- /Users/buck/repo/getsentry/sentry/.venv/bin/python3
cachedir: .pytest_cache
metadata: {'Python': '3.13.1', 'Platform': 'macOS-15.5-arm64-arm-64bit-Mach-O', 'Packages': {'pytest': '8.1.2', 'pluggy': '1.5.0'}, 'Plugins': {'fail-slow': '0.3.0', 'time-machine': '2.16.0', 'json-report': '1.5.0', 'metadata': '3.1.1', 'xdist': '3.0.2', 'django': '4.9.0', 'pytest_sentry': '0.3.0', 'anyio': '3.7.1', 'rerunfailures': '15.0', 'cov': '4.0.0'}}
django: version: 5.2.1
rootdir: /Users/buck/repo/getsentry/sentry
configfile: pyproject.toml
plugins: fail-slow-0.3.0, time-machine-2.16.0, json-report-1.5.0, metadata-3.1.1, xdist-3.0.2, django-4.9.0, pytest_sentry-0.3.0, anyio-3.7.1, rerunfailures-15.0, cov-4.0.0
collected 1 item

tests/snuba/api/endpoints/test_organization_trace_meta.py::OrganizationEventsTraceMetaEndpointTest::test_bad_ids PASSED [100%]
tests/snuba/api/endpoints/test_organization_trace_meta.py::OrganizationEventsTraceMetaEndpointTest::test_bad_ids ERROR [100%]

====================================== ERRORS ======================================
____ ERROR at teardown of OrganizationEventsTraceMetaEndpointTest.test_bad_ids _____
tests/conftest.py:97: in unclosed_threads
    _assert_same_pthreads(orig_pthreads, _get_pthreads())
tests/conftest.py:79: in _assert_same_pthreads
    assert new_diff == old_diff  # both should be empty
E   assert {pthread(id=5, user_time=0.000474, system_time=0.00022), pthread(id=6, user_time=0.000477, system_time=0.000229), pthread(id=8, user_time=0.000409, system_time=0.000149), pthread(id=7, user_time=0.000476, system_time=0.000194)} == set()
E
E     Extra items in the left set:
E     pthread(id=5, user_time=0.000474, system_time=0.00022)
E     pthread(id=6, user_time=0.000477, system_time=0.000229)
E     pthread(id=8, user_time=0.000409, system_time=0.000149)
E     pthread(id=7, user_time=0.000476, system_time=0.000194)
E
E     Full diff:
E     - set()
E     + {
E     +     pthread(id=5, user_time=0.000474, system_time=0.00022),
E     +     pthread(id=6, user_time=0.000477, system_time=0.000229),
E     +     pthread(id=7, user_time=0.000476, system_time=0.000194),
E     +     pthread(id=8, user_time=0.000409, system_time=0.000149),
E     + }

The above exception was the direct cause of the following exception:
tests/conftest.py:102: in unclosed_threads
    raise e2 from e1
tests/conftest.py:100: in unclosed_threads
    assert _get_python_threads() == orig_python_threads
E   assert frozenset({<Thread(Thread-2 (worker), started daemon 6195097600)>, <Thread(_make_rpc_requests_0, started 6262403072)>, <_MainThread(MainThread, started 8745787136)>, <Thread(Thread-1 (run_server), started daemon 6178271232)>, <Thread(_make_rpc_requests_2, started 6296055808)>, <Thread(_make_rpc_requests_1, started 6279229440)>, <Thread(_make_rpc_requests_3, started 6312882176)>}) == frozenset({<Thread(Thread-2 (worker), started daemon 6195097600)>, <_MainThread(MainThread, started 8745787136)>, <Thread(Thread-1 (run_server), started daemon 6178271232)>})
E
E     Extra items in the left set:
E     <Thread(_make_rpc_requests_2, started 6296055808)>
E     <Thread(_make_rpc_requests_0, started 6262403072)>
E     <Thread(_make_rpc_requests_3, started 6312882176)>
E     <Thread(_make_rpc_requests_1, started 6279229440)>
E
E     Full diff:
E       frozenset({
E           <Thread(Thread-1 (run_server), started daemon 6178271232)>,
E           <Thread(Thread-2 (worker), started daemon 6195097600)>,
E     +     <Thread(_make_rpc_requests_2, started 6296055808)>,
E     +     <Thread(_make_rpc_requests_3, started 6312882176)>,
E     +     <Thread(_make_rpc_requests_0, started 6262403072)>,
E     +     <Thread(_make_rpc_requests_1, started 6279229440)>,
E           <_MainThread(MainThread, started 8745787136)>,
E       })
------------------------------ Captured stderr setup -------------------------------
Creating test database for alias 'default' ('test_region')...
Creating test database for alias 'control' ('test_control')...
Creating test database for alias 'secondary' ('test_secondary')...
----------------------------- Captured stderr teardown -----------------------------
Destroying test database for alias 'default' ('test_region')...
Destroying test database for alias 'control' ('test_control')...
Destroying test database for alias 'secondary' ('test_secondary')...
============================= short test summary info ==============================
ERROR tests/snuba/api/endpoints/test_organization_trace_meta.py::OrganizationEventsTraceMetaEndpointTest::test_bad_ids - assert frozenset({<Thread(Thread-2 (worker), started daemon 6195097600)>, <Thre...
=========================== 1 passed, 1 error in 10.37s ============================
exit code: 1
duration: 16.094 seconds