Update google-cloud-bigtable generated files (#2615)
Update google-cloud-bigtable generated files (#2615)

* Add synth.metadata file.
dazuma/google-cloud-ruby,dazuma/google-cloud-ruby,dazuma/google-cloud-ruby,dazuma/google-cloud-ruby,quartzmo/google-cloud-ruby,quartzmo/google-cloud-ruby,googleapis/google-cloud-ruby,dazuma/google-cloud-ruby,quartzmo/google-cloud-ruby,googleapis/google-cloud-ruby,googleapis/google-cloud-ruby,dazuma/google-cloud-ruby,googleapis/google-cloud-ruby,blowmage/gcloud-ruby,quartzmo/google-cloud-ruby,quartzmo/google-cloud-ruby,quartzmo/google-cloud-ruby,googleapis/google-cloud-ruby,googleapis/google-cloud-ruby