Remove 'Job failed (system failure)' expected error message

What does this MR do and why?

Remove Job failed (system failure) from expected error message in runner output when a secrets cannot be fetched by a CI job.

This fixes broken CI pipelines in gitlab.

References

gitlab-org/quality/analytics/ci-health-incidents#1290 (closed)

gitlab-org/quality/analytics/ci-health-incidents#1291 (closed)

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