OECDRegionalDemography_Population| Fixed missing data issue

[Ashwani725]

This PR is raised to fix validation failure in OECDRegionalDemography_Population job due to change in working age cohorts in upstream source.

Support broad working-age cohorts (20-64, 25-54, 55-64) in OECD Regional Demography Population

Add support for OECD regional demography broad working-age population cohorts:

• Added StatVar mappings for 20-64, 25-54, and 55-64 years (Total, Male, and Female variants).
• Added schema definitions for new non-canonical StatVars in OECD_population_stat_vars.mcf (deduplicated against existing canonical Data Commons schema nodes).
• Configured date freshness validation rules via validation_config.json to ensure broad cohorts have data through at least 2025 and standard 5-year cohorts through at least 2023.
• Updated sample data and golden fixtures. Note: Upstream OECD currently reports data exclusively for Total (_T) for broad age groups; gender-stratified mappings are preserved for future-proofing and remain unpopulated in current outputs.

Test result:
Test Cloud Batch Job
Test GCS Bucket
CL link

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[gemini-code-assist]

Code Review

This pull request introduces new statistical variables for age groups 20-64, 25-54, and 55-64, including gender-specific breakdowns, and updates the associated column mappings and golden data. Additionally, a new validation configuration file is added to the manifest. The reviewer recommended updating the rule_id in the validation configuration for consistency and noted that the expected test files must be updated to reflect these schema changes to prevent unit test failures.

[saanikaaa]

Can we pls run differ to validated our changes

[Ashwani725]

Can we pls run differ to validated our changes

Please find the attached differ_summary report
differ_summary report

[saanikaaa]

/gcbrun

[balit-raibot]

/gcbrun