metricscaler sample: 'test_scale_bigtable' fails in setup with NotFound #394

    def test_scale_bigtable(instance):
        bigtable_client = bigtable.Client(admin=True)

        instance = bigtable_client.instance(BIGTABLE_INSTANCE)
>       instance.reload()

metricscaler_test.py:109:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
../../google/cloud/bigtable/instance.py:364: in reload
    instance_pb = self._client.instance_admin_client.get_instance(
../../google/cloud/bigtable_admin_v2/services/bigtable_instance_admin/client.py:605: in get_instance
    response = rpc(request, retry=retry, timeout=timeout, metadata=metadata,)
.nox/py-3-8/lib/python3.8/site-packages/google/api_core/gapic_v1/method.py:145: in __call__
    return wrapped_func(*args, **kwargs)
.nox/py-3-8/lib/python3.8/site-packages/google/api_core/retry.py:285: in retry_wrapped_func
    return retry_target(
.nox/py-3-8/lib/python3.8/site-packages/google/api_core/retry.py:188: in retry_target
    return target()
.nox/py-3-8/lib/python3.8/site-packages/google/api_core/grpc_helpers.py:69: in error_remapped_callable
    six.raise_from(exceptions.from_grpc_error(exc), exc)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

value = None
from_value = <_InactiveRpcError of RPC that terminated with:
	status = StatusCode.NOT_FOUND
	details = "Instance projects/python-do...ge":"Instance projects/python-docs-samples-tests/instances/metric-scale-test-a60739a9-3 not found.","grpc_status":5}"
>

>   ???
E   google.api_core.exceptions.NotFound: 404 Instance projects/python-docs-samples-tests/instances/metric-scale-test-a60739a9-3 not found.

<string>:3: NotFound