Attempt fix for undefined job bug [RUN ALL RSPEC] [RUN AS-IF-FOSS]

What does this MR do?

Having looked into Sentry bugs from flipping the pipeline feature flag (https://sentry.gitlab.net/gitlab/gitlabcom-clientside/issues/2534640/?query=is%3Aunresolved%20has%3Acomponent, https://sentry.gitlab.net/gitlab/gitlabcom-clientside/issues/2534670/?query=is%3Aunresolved%20has%3Acomponent [internal]), it appears that somehow a job is appearing as undefined in an an array.

These changes introduce the expected mitigation and a second option behind a feature flag so we can test them both.

Screenshots (strongly suggested)

No visual changes.

Does this MR meet the acceptance criteria?

Conformity

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Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.

Related to #276949 (closed)