system-test/pg-connect.ts: open IAM connection and retrieves standard pg tables failed

[flaky-bot]

Note: #284 was also for this test, but it was closed more than 10 days ago. So, I didn't mark it flaky.

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commit: 7655fd8
buildURL: https://github.com/GoogleCloudPlatform/cloud-sql-nodejs-connector/actions/runs/20319666801
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.

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When run at the same commit (7655fd8), this test passed in one build (https://github.com/GoogleCloudPlatform/cloud-sql-nodejs-connector/actions/runs/20319666801) and failed in another build (https://github.com/GoogleCloudPlatform/cloud-sql-nodejs-connector/actions/runs/20319666801).