ci: fix HA-harness tests — asyncio_mode=auto (pytest.ini), per-module enable_custom_integrations fixture instead of a global autouse that broke sync tests

tests_backend/conftest.py

@@ -1,7 +1,6 @@
-"""Shared fixtures. HA-harness tests are skipped when homeassistant is not installed
-(the local sandbox has Python 3.10; CI runs them on 3.13 with
-pytest-homeassistant-custom-component)."""
-import pytest
+"""Shared test config. HA-harness tests (test_ha_*.py) are skipped when
+homeassistant is not installed: the local sandbox has Python 3.10, CI runs them
+on 3.13 with pytest-homeassistant-custom-component."""
 
 try:
     import homeassistant  # noqa: F401
@@ -10,10 +9,3 @@ except ImportError:
     HAS_HA = False
 
 collect_ignore_glob = [] if HAS_HA else ["test_ha_*.py"]
-
-
-if HAS_HA:
-    @pytest.fixture(autouse=True)
-    def auto_enable_custom_integrations(enable_custom_integrations):
-        """Allow loading custom_components in the test hass."""
-        yield