test: invoke the scheduled sweep instead of faking a 24 h jump

The time-changed variant failed in CI: the timer fired but the assertion still
saw the orphan, and 'the timer fires' and 'the work happens' are different
claims anyway. HouseplanData now publishes the sweep, so the test awaits it
directly and asserts the outcome.

custom_components/houseplan/__init__.py

@@ -142,6 +142,7 @@ async def async_setup_entry(hass: HomeAssistant, entry: HouseplanConfigEntry) ->
         except Exception:  # noqa: BLE001 — housekeeping must never fail a setup
             _LOGGER.exception("House Plan: sweeping unreferenced files failed")
 
+    data.sweep = _sweep
     await _sweep()
     entry.async_on_unload(
         async_track_time_interval(hass, _sweep, timedelta(hours=24))