refactor: Refactor Places Insights spot-check notebook

[henrikvalv3]

Summary

This PR refactors the places_insights_spot_check_results_using_functions.ipynb notebook to improve query performance, reduce API costs, and streamline the geospatial visualization workflow.

Key Changes

• Query Optimization: Replaced the full London boundary query with a deterministic 5km radius buffer around Central London (Charing Cross) at H3 Resolution 9.
• Code Modernization: Switched to using %%bigquery magic commands for cleaner SQL execution and GeoPandas conversion.
• API Efficiency: Updated the Places API fetch loop to request only the necessary fields (formattedAddress, location, displayName, googleMapsUri), removing unused rating data to optimize payload size.
• Map Logic: Centralized Google Maps Tiles API session handling (tokens, attribution, and logo assets) into a single setup cell to prevent redundant requests.
• UX Improvements: Added "Open in Colab/BigQuery Studio" badges and updated markdown instructions to match the new logic.