Fix broken gsutil in Variants Docker image [VS-888]

[mcovarr]

TBH I'm not sure what went wrong with the previous image, I just re-baked a new one with the current version of gcloud-sdk and that seems to be working (or at least gsutil does not immediately explode).

Test run here https://job-manager.dsde-prod.broadinstitute.org/jobs/016779a9-62d0-4195-9598-5f0eee559d99

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (ah_var_store@4ab6bde). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files

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[koncheto-broad]

looks inoffensive as a PR, but I also can't see what exactly caused or fixed the issue we saw yesterday