[Unit Tests] Increase testGetAuthCookie timeout to cope with execution time in CI

[tiagomar]

This is a follow up PR to #22822.

While a typical test execution time in local stays under 0.2 seconds (0.148s for the first run, averaging 0.002 in subsequent runs), on CI the numbers are a bit worse.

In the last 28 days, the failed runs were generaly over 1s, 95% under 2.63s, but we still got a singe 3.75s run.

This PR sets the timeout to 5s for this test, which is not too high to compromise the Unit Tests performance.

[twstokes]

LGTM @tiagomar! Fingers crossed 🤞 that it just needs more time to spin up IO sometimes.

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