Revert "Revert "Use recorder executor in demo (#69327)" (#69334)" (#69545)

- We have found the issue causing the CI failures and its
  being solved in #69410.

This reverts commit 28350b9792.

homeassistant/components/demo/__init__.py

@@ -5,6 +5,7 @@ from random import random
 
 from homeassistant import config_entries, setup
 from homeassistant.components import persistent_notification
+from homeassistant.components.recorder import get_instance
 from homeassistant.components.recorder.statistics import (
     async_add_external_statistics,
     get_last_statistics,
@@ -245,7 +246,7 @@ async def _insert_statistics(hass):
     }
     statistic_id = f"{DOMAIN}:energy_consumption"
     sum_ = 0
-    last_stats = await hass.async_add_executor_job(
+    last_stats = await get_instance(hass).async_add_executor_job(
         get_last_statistics, hass, 1, statistic_id, True
     )
     if "domain:energy_consumption" in last_stats: