fix: Prevent parser startup before scanner job is visible - #3795

Description

Change checkIfAllJobsCompleted so that a list containing no Jobs is explicitly incomplete; completion must require at least one observed Job and successful status for every observed Job. Keep the existing precedence in which any BackoffLimitExceeded Job reports failure and any non-succeeded Job reports incomplete, so all three production callers—the scanner, parser, and hook reconciliation paths—remain conservative during cache-observation gaps. Extend the existing table of focused helper tests with the empty-list case, while retaining coverage for all-succeeded, mixed/incomplete, and failed lists.

The scan reconciler decides whether scanner, parser, and hook Jobs have finished through checkIfAllJobsCompleted. That helper initializes its aggregate result as completed, so an empty Job list is interpreted as successful even though no Job has reported success. During the short interval in which the controller cache has not yet observed a newly created scanner Job, this can advance the Scan to ScanCompleted and start the parser before the scanner uploads its raw result, producing an intermittent MinIO NoSuchKey error. The maintainer reproduced the rare behavior and identified this helper as the relevant decision point.

Closes #3139

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