Update notebook for Google Semantic Retriever (#9824)

* Update Auth

* Update auth for notebook

* fix lint issue

* Update auth links

* lint

* remove extra metadata

* Fix a race condition between ingestion and querying

* Switch to Gemini

* Minor update on comment

* Update colab

* remove unknown file

* revert old setting

* remove unused file

* Use a random value instead of asking user for one

* code review

* Update notebook

* Removed LLMPredictor

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Co-authored-by: Michael Chen <tymichaelchen@gmail.com>