GCS+gRPC integration fails

This failure indicates the test used more memory than expected:

```
google/cloud/storage/tests/object_read_large_integration_test.cc:87: Failure
Expected: (current_rss) <= (tolerance), actual: 492998656 vs 492855296
```

* GCB: https://console.cloud.google.com/cloud-build/builds;region=us-east1/fe4be0b0-03fc-47e1-82ab-d05968016842;tab=detail?project=cloud-cpp-testing-resources
* Raw: https://storage.googleapis.com/cloud-cpp-community-publiclogs/logs/google-cloud-cpp/main/6505814e75b598e4e2f492f9bbe2c827942143bf/fedora-latest-bazel-asan/log-fe4be0b0-03fc-47e1-82ab-d05968016842.txt

It could be because the test needs adjustment for gRPC, or because there is a real leak somewhere. I suspect the first, since this is a flake.