Add Integration Test or Sample for ML.PREDICT TVF usage to generate embeddings within Spanner

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Is your feature request related to a problem? Please describe.

• Provide a working example to generate embeddings using ML.PREDICT TVF function would simplify how customers can use ML.PREDICT to query, update embeddings inside Spanner.

Describe the solution you'd like

• Add a integration test with sample queries of ML.PREDICT

Describe alternatives you've considered

• Add a Sample in the snippets.

Additional context

• NA