chore,refaactor(egen): minor changes to sdk feature store pandas notebook

[sriramya2610]

This PR includes the following updates:

1. Adds Colab Enterprise link and other structural changes from the new template.
2. Changes REGION variable name to LOCATION.
3. Removed os.getenv("IS_TESTING") while cleanup bucket.
4. Adds comments for cells needed.

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• Use the notebook template as a starting point.
• Follow the style and grammar rules outlined in the above notebook template.
• Verify the notebook runs successfully in Colab since the automated tests cannot guarantee this even when it passes.
• Passes all the required automated checks. You can locally test for formatting and linting with these instructions.
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• This notebook has been added to the CODEOWNERS file under the Official Notebooks section, pointing to the author or the author's team.
• The Jupyter notebook cleans up any artifacts it has created (datasets, ML models, endpoints, etc) so as not to eat up unnecessary resources.

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[kittyabs]

no edits required

[katiemn]

/gcbrun