[core] Use placement new allocation for Pvariables (#15079)

Co-authored-by: J. Nick Koston <nick@home-assistant.io>
Co-authored-by: J. Nick Koston <nick@koston.org>

tests/component_tests/binary_sensor/test_binary_sensor.py

@@ -15,7 +15,7 @@ def test_binary_sensor_is_setup(generate_main):
     )
 
     # Then
-    assert "new gpio::GPIOBinarySensor();" in main_cpp
+    assert "static gpio::GPIOBinarySensor *const" in main_cpp
     assert "App.register_binary_sensor" in main_cpp