Download script is changed to add all quarters of data

[Krishnam24maheshwari]

This PR resolves the deletions problems caused by 13-quarter rolling window logic as per the API we are using to download data.

Changes Made in brazil_download_script.py:
1. Replaced the 13-quarter rolling window logic with get_available_periods() and different API.
2. Fixed the baseline start period explicitly to 202201 (Q1 2022) onwards through the latest available quarter.
3. Applied this updated period range across all four dataset categories (Average_Real_Income, Mass_Income, Population_Economic_sector, and Employment_And_Unemployment_Labor_Force), preserving all 2022 records and resolving false deletion validation errors.

PR Checklist -
https://docs.google.com/spreadsheets/d/1RD4U94SM2mLcjSZRLjJHVliF737fScBH4rsDU_Pu_hk/edit?gid=1086229089#gid=1086229089

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[gemini-code-assist]

Code Review

This pull request refactors the Brazil SIDRA IBGE download script, replacing the Selenium-based browser automation with direct API calls using the requests library and reshaping the data into Excel files using pandas. The review feedback recommends improving performance, security, and robustness by using a global requests.Session with connection pooling and retries, re-enabling SSL verification, and adding explicit guard checks to safely parse the API responses.

[pulkeet-wq]

Few action items:

1. Update README files
2. Add try except blocks specifically while downloading the data
3. Add proper comments to the code
4. Add goldens