AodPolicy: Fix service leak

Fixes an issue where the AlwaysOnDisplayPolicy leaked a service
context, and with it the entirety of DozeMachine, preventing
wakelocks from being GCed and preventing them from being
fallback-released.

Bug: 78402666
Test: Toggle screen on and off a few times, verify that DozeService is not being leaked.
Change-Id: Ie3ad67c2d0c83760f4d04a53394fab4a3a35d6bc
diff --git a/packages/SystemUI/src/com/android/systemui/doze/DozeService.java b/packages/SystemUI/src/com/android/systemui/doze/DozeService.java
index aa26419..7339304 100644
--- a/packages/SystemUI/src/com/android/systemui/doze/DozeService.java
+++ b/packages/SystemUI/src/com/android/systemui/doze/DozeService.java
@@ -62,6 +62,7 @@
     public void onDestroy() {
         Dependency.get(PluginManager.class).removePluginListener(this);
         super.onDestroy();
+        mDozeMachine = null;
     }
 
     @Override