[Image Sequence] Fix wrong thumbnails

We need to keep the "time-to-live" (ttl) in the thumb producer otherwise
the default of 25 will be used, which is wrong

src/mltcontroller/clipcontroller.cpp

@@ -351,12 +351,13 @@ const char *ClipController::getPassPropertiesList(bool passLength)
         return "kdenlive:proxy,kdenlive:originalurl,kdenlive:multistreams,rotate,force_aspect_num,force_aspect_den,force_aspect_ratio,force_fps,force_"
                "progressive,force_tff,threads,"
                "force_"
-               "colorspace,set.force_full_luma,file_hash,autorotate,disable_exif,xmldata,video_index,audio_index,set.test_image,set.test_audio";
+               "colorspace,set.force_full_luma,file_hash,autorotate,disable_exif,xmldata,video_index,audio_index,set.test_image,set.test_audio,ttl";
     }
     return "kdenlive:proxy,kdenlive:originalurl,kdenlive:multistreams,rotate,force_aspect_num,force_aspect_den,force_aspect_ratio,force_fps,force_progressive,"
            "force_tff,threads,"
            "force_"
-           "colorspace,set.force_full_luma,templatetext,file_hash,autorotate,disable_exif,xmldata,length,video_index,audio_index,set.test_image,set.test_audio";
+           "colorspace,set.force_full_luma,templatetext,file_hash,autorotate,disable_exif,xmldata,length,video_index,audio_index,set.test_image,set.test_audio,"
+           "ttl";
 }
 
 QMap<QString, QString> ClipController::getPropertiesFromPrefix(const QString &prefix, bool withPrefix)