Fixes failing test so we can publish

[techiejd]

Note

Improves reliability of the failed validation test by isolating DB state and asserting expected error outcomes.

• Use createTestDb and point connectionString to failed_validation_test to isolate the database
• Ensure vectorization job runs by enabling cron and waitForVectorizationJobs
• Add assertions: latest payload-jobs entry for payloadcms-vectorize:vectorize has hasError = true with error mentioning chunk and Invalid indices: 1
• Verify no embeddings were created by checking count in default collection

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