sessions: should get 200 failed

[flaky-bot]

Note: #482 was also for this test, but it was closed more than 10 days ago. So, I didn't mark it flaky.

---

commit: b889e24
buildURL: https://console.cloud.google.com/cloud-build/builds;region=global/400bee98-14a5-483e-ac1a-3d416c45768d?project=firestore-nodejs-getting-start
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 (b889e24), this test passed in one build (https://console.cloud.google.com/cloud-build/builds;region=global/f23af42d-df99-4736-9c1b-e72168c21108?project=firestore-nodejs-getting-start) and failed in another build (https://console.cloud.google.com/cloud-build/builds;region=global/400bee98-14a5-483e-ac1a-3d416c45768d?project=firestore-nodejs-getting-start).