Remove powerwall attributes no longer present in latest firmware (#36667)

tests/components/powerwall/test_binary_sensor.py

@@ -33,9 +33,6 @@ async def test_sensors(hass):
     state = hass.states.get("binary_sensor.powerwall_status")
     assert state.state == STATE_ON
     expected_attributes = {
-        "region": "IEEE1547a:2014",
-        "grid_code": "60Hz_240V_s_IEEE1547a_2014",
-        "nominal_system_power_kW": 25,
         "friendly_name": "Powerwall Status",
         "device_class": "power",
     }