bigtable.hbase.async.TestAsyncCreateTable: testAsyncGetRegions failed

Note: #3138 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: ebec77c7a919188fe9dfe5a5ff9c17735a2a03aa
buildURL: [Build Status](https://source.cloud.google.com/results/invocations/3827e8e5-35c4-4563-8704-0a0eadd9a148), [Sponge](http://sponge2/3827e8e5-35c4-4563-8704-0a0eadd9a148)
status: failed

Start with bigtable.hbase.async.TestAsyncCreateTable.testAsyncGetRegions and the failed build linked in the issue, using commit ebec77c7a919188fe9dfe5a5ff9c17735a2a03aa as the reference point. Reproduce the failure and inspect the available build details; done means the cause is identified and the test failure is addressed or its flaky status is established.

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