Fix too many items showing up in playback history (#8476)

### Description

Fix too many items showing up in playback history. When continuous
playback is disabled, we still load the next episode to update the media
session. However, we should not mark it as started. Otherwise we clutter
the playback history with episodes that have not been played.

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

@@ -236,7 +236,8 @@ public class Media3PlaybackService extends MediaLibraryService {
             } else {
                 EventBus.getDefault().post(BufferUpdateEvent.ended());
             }
-            if (playbackState == Player.STATE_READY || playbackState == Player.STATE_ENDED) {
+            if ((playbackState == Player.STATE_READY && player.getPlayWhenReady())
+                    || playbackState == Player.STATE_ENDED) {
                 saveCurrentPosition();
             }
             if (playbackState == Player.STATE_ENDED && currentPlayable != null) {