Fix bq-to-vcf-option-customized-export test (#541)
Fix bq-to-vcf-option-customized-export test (#541)

Also make bq_to_vcf to produce correctly ordered call_names when they are
provided. This is due to the Beam-2.18.0 known issue of not preserving the
order unless `reshuffle=False` is provided. For more information please
refer to:
https://beam.apache.org/blog/2020/01/13/beam-2.18.0.html
googlegenomics/gcp-variant-transforms,googlegenomics/gcp-variant-transforms