daily_rates not handling Organisation with duplicate account_locator

[seediang]

Our snowflake organisation has multiple accounts with the same account_locator. This results in rates from either account turning up in the daily_rates table, which means daily_spend is not aligning with the snowflake bill.

I had a quick look at the code and the fix looks like an additional filter that is effectively region = current_region() needs to be added to the daily_rates model. I will have look and see if I can create a suitable pull request.