Exclude shard_encrypted_collection.js from CSRS stepdown suite

The tests in shard_encrypted_collection.js expect the sharded cluster to return InvalidOptions error code when trying to shard/reshard/refine using an encrypted field as the shard key. In the CSRS stepdown suite, this error response is not always guaranteed to be InvalidOptions, as the config server can fail and cause the overall reshard operation to return ReshardCollectionAborted.