Bigtable backups: "before all" hook for "should create backup of a table (from cluster)" failed

[flaky-bot[bot]]

Note: #1056 was also for this test, but it was closed more than 10 days ago. So, I didn't mark it flaky.

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commit: 2129312401bf9f5b8e51b13ac576cb765de401df buildURL: Build Status, Sponge status: failed