Unblock users when sleep timer acts up (#8593)

### Description

Unblock users when sleep timer acts up. Release mode only, we want to
handle/fix this as a bug if it happens.

### Checklist
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playback/service/src/main/java/de/danoeh/antennapod/playback/service/Media3PlaybackService.java

@@ -721,6 +721,9 @@ public class Media3PlaybackService extends MediaLibraryService {
         if (sleepTimer != null) {
             sleepTimer.stop();
             sleepTimer = null;
+        } else if (!BuildConfig.DEBUG) {
+            // Unblock user in case we somehow got into an inconsistent state
+            EventBus.getDefault().postSticky(SleepTimerUpdatedEvent.cancelled());
         }
         if (player != null) {
             applyVolumeAdaption(1.0f);