Fix timer.finish to cancel callback (#48549)

Timer.finish doesn't cancel the callback, which can lead to incorrect early cancellation of the timer if it is subsequently restarted. 

Bug reported here: https://community.home-assistant.io/t/timer-component-timer-stops-before-time-is-up/96038

homeassistant/components/timer/__init__.py

@@ -327,7 +327,9 @@ class Timer(RestoreEntity):
         if self._state != STATUS_ACTIVE:
             return
 
-        self._listener = None
+        if self._listener:
+            self._listener()
+            self._listener = None
         self._state = STATUS_IDLE
         self._end = None
         self._remaining = None