SerializedShuffleHandle is a BaseShuffleHandle that
SortShuffleManager uses when canUseSerializedShuffle (when requested to register a shuffle and BypassMergeSortShuffleHandles could not be selected).
SortShuffleManager to use UnsafeShuffleWriter when requested for a ShuffleWriter.
SerializedShuffleHandle takes the following to be created:
- Shuffle ID
SerializedShuffleHandle is created when:
SortShuffleManageris requested for a ShuffleHandle (for the ShuffleDependency)