bigtable: TestIntegration_TableDeletionProtection failed

Note: #11393 was also for this test, but it was closed more than 10 days ago. So, I didn't mark it flaky. ---- commit: 30b1dfa0db7fabab0296933c8a021169884e2c0b buildURL: [Build Status](https://source.cloud.google.com/results/invocations/b7e95329-421f-4610-8ed1-361712bd2fdd), [Sponge](http://sponge2/b7e95329-421f-4610-8ed1-361712bd2fdd) status: failed