Correct timescale of edit list duration parsing for stbl atoms.

We currently apply the track.timescale whereas we should be applying the
track.movieTimescale. The parsing for the trak atom does this correctly
and the duration from the trak atom currently always takes precedence over the
durations from the stbl atoms as it's always larger.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=212421687

library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java

@@ -436,7 +436,8 @@ import java.util.List;
       }
       pts += track.editListDurations[i];
     }
-    long editedDurationUs = Util.scaleLargeTimestamp(pts, C.MICROS_PER_SECOND, track.timescale);
+    long editedDurationUs =
+        Util.scaleLargeTimestamp(pts, C.MICROS_PER_SECOND, track.movieTimescale);
     return new TrackSampleTable(
         track,
         editedOffsets,