fix: inspect returned grpc::Status (#5558)
fix: inspect returned grpc::Status (#5558)

In some environments `grpc::Status` is marked as "must_use_result", and
these test lines would cause a breakage due to `-Wunused-result` if we
didn't do something with the `grpc::Status` that's returned from these
`LogWrapper()` calls.
googleapis/google-cloud-cpp,googleapis/google-cloud-cpp,googleapis/google-cloud-cpp,googleapis/google-cloud-cpp