[Bug]: Infinite credit spend in grounding_with_vais example

### File Name

gemini/grounding/grounding_with_vais.ipynb

### What happened?

Infinite credit spend in one of two examples for the Vertex Search feature. Not a fun surprise.

This code is missing a break condition and encourages the end user to let it run unattended, which will result in an infinite loop of queries that incur costs.

https://github.com/GoogleCloudPlatform/generative-ai/blob/312646ea8151720d2e65d7e37f0b20268262fb61/gemini/grounding/grounding_with_vais.ipynb#L420-L434

### Relevant log output

```shell

```

### Code of Conduct

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