tests.system: test_listing_topic_subscriptions[grpc-grpc] failed

[flaky-bot]

Note: #872 was also for this test, but it was closed more than 10 days ago. So, I didn't mark it flaky.

---

commit: 5aca748
buildURL: Build Status, Sponge
status: failed

[flaky-bot]

Looks like this issue is flaky. 😟

I'm going to leave this open and stop commenting.

A human should fix and close this.

---

When run at the same commit (5aca748), this test passed in one build (Build Status, Sponge) and failed in another build (Build Status, Sponge).

[mukund-ananthu]

This happened due to a 504 deadline exceed:

args = (name: "projects/precise-truck-742/subscriptions/sub-3.1722717552748"
topic: "projects/precise-truck-742/topics/topic-1.1722717539886"
,)
kwargs = {'metadata': [('x-goog-request-params', 'name=projects/precise-truck-742/subscriptions/sub-3.1722717552748'), ('x-goog-api-client', 'gl-python/3.12.0 grpc/1.66.0rc2 gax/2.19.1 gccl/2.23.0')], 'timeout': 60.0}

    @functools.wraps(callable_)
    def error_remapped_callable(*args, **kwargs):
        try:
            return callable_(*args, **kwargs)
        except grpc.RpcError as exc:
>           raise exceptions.from_grpc_error(exc) from exc
E           google.api_core.exceptions.DeadlineExceeded: 504 Deadline Exceeded

[.nox/system-3-12/lib/python3.12/site-packages/google/api_core/grpc_helpers.py:78](https://cs.corp.google.com/piper///depot/google3/.nox/system-3-12/lib/python3.12/site-packages/google/api_core/grpc_helpers.py?l=78): DeadlineExceeded
- generated xml file: /tmpfs/src/github/python-pubsub/system_3.12_sponge_log.xml -
===Flaky Test Report===

which according to the Pub/Sub documentation is a retryable error code: https://cloud.google.com/pubsub/docs/reference/error-codes