fix sql validator BIS_CentralBankPolicyRate

[niveditasing]

Added golden rules & also modified the SQL_VALIDATOR queries as per new differ format

Testing results of SQL_VALIDATOR queries : https://storage.mtls.cloud.google.com/datcom-import-test/statvar_imports/bis/bis_central_bank_policy_rate/BIS_CentralBankPolicyRate/2026_07_17T03_26_57_208559_07_00/input0/validation/validation_output.csv

[gemini-code-assist]

Code Review

This pull request updates the validation configuration by replacing variableMeasured with StatVar in SQL queries and switching the deletion validator from DELETED_RECORDS_COUNT to DELETED_RECORDS_PERCENT with a threshold of 0.1. The reviewer pointed out that the DELETED_RECORDS_PERCENT validator uses a 0-100 scale, meaning a threshold of 0.1 restricts deletions to 0.1% instead of 10%. They suggested adjusting the threshold to 10 if a 10% limit was intended.

[pulkeet-wq]

LGTM