Fix flaky Search::Zoekt::SchedulingService spec

What does this MR do and why?

related to gitlab-org/quality/engineering-productivity/jennli-test-triage-automation-setup#2 and #460384 (closed)

Fix a flaky-testtransient bug

MR acceptance checklist

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Screenshots or screen recordings

N/A

How to set up and validate locally

Relying on pipelines here