Update partial download test (#2341)
Update partial download test (#2341)

This test fails occasionally on CI. We aren't sure why.
We have a custom message to help dignose, but we have seen some
download verification errors when it gets proc'd.
Set the download to verify: :none to avoid the verification errors.
Update the custom message to show a bit more information.
dazuma/google-cloud-ruby,quartzmo/gcloud-ruby,quartzmo/google-cloud-ruby,quartzmo/google-cloud-ruby,quartzmo/google-cloud-ruby,blowmage/gcloud-ruby,googleapis/google-cloud-ruby,googleapis/google-cloud-ruby,quartzmo/google-cloud-ruby,googleapis/google-cloud-ruby,dazuma/google-cloud-ruby,googleapis/google-cloud-ruby,dazuma/google-cloud-ruby,googleapis/google-cloud-ruby,dazuma/google-cloud-ruby,quartzmo/google-cloud-ruby,quartzmo/google-cloud-ruby,googleapis/google-cloud-ruby,dazuma/google-cloud-ruby,dazuma/google-cloud-ruby