Fix colorTemperatureInKelvin in Alexa report when light is off (#27107)

* Fixes #26405 Return None if light state is off since attribute is unavailable, prevents property from being reported with invalid value of 0.

* Update Test to check property is not reported when light state is off.

homeassistant/components/alexa/capabilities.py

@@ -326,7 +326,7 @@ class AlexaColorTemperatureController(AlexaCapibility):
             return color_util.color_temperature_mired_to_kelvin(
                 self.entity.attributes["color_temp"]
             )
-        return 0
+        return None
 
 
 class AlexaPercentageController(AlexaCapibility):

tests/components/alexa/test_capabilities.py

@@ -294,8 +294,8 @@ async def test_report_colored_temp_light_state(hass):
     )
 
     properties = await reported_properties(hass, "light.test_off")
-    properties.assert_equal(
-        "Alexa.ColorTemperatureController", "colorTemperatureInKelvin", 0
+    properties.assert_not_has_property(
+        "Alexa.ColorTemperatureController", "colorTemperatureInKelvin"
     )