fix(api): stream a notice instead of erroring when verification logs requested before Job starts

[alombardo4]

Description

Closes #7203

Until Argo Rollouts records the first measurement for a job metric, an AnalysisRun's status has no Job namespace/name, and requesting logs during that window returns an error the UI surfaced as an alert. When the run is not yet complete and the Job cannot be resolved, respond with an SSE event saying logs are not available yet. Completed runs with missing Job metadata still error as before.

Checklist

Eligibility

• Linked to an existing issue with no blocking labels (kind/proposal, needs discussion, needs research, maintainer only, area/security, size/large, size/x-large, size/xx-large).
• Changes documentation only.
• Changes ten lines or fewer.

Quality

• Adds or updates corresponding tests.
• Adds or updates corresponding documentation.

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• Entirely by an AI. No human has reviewed this prior to opening the PR.

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