Add country to ads insights country breakdown PK

[dmosorast]

Description of change

It seems that ads_insights_country is missing the country property from its Primary Key. This may cause targets that deduplicate based on the PK to have incorrect totals in situations where the values that were split by country get deduplicated back to the record as defined by the base insights PK.

Manual QA steps

• None, this is to track what this will look like while I confirm that this is indeed an issue.

Risks

• Medium, it's unclear what downstream effect changing the primary key will have, depending on target, but it may be safer since it's additive.

Rollback steps

• revert this branch

[lserraga]

I've encountered this issue with a redshift target https://github.com/transferwise/pipelinewise-target-redshift. Resulting in ads_insights_country only having one row per day (1 country), regardless of how much data and countries tap-facebook extracted

[shyamodedraRK]

Same issue here, surely this report does not work as it stands so the breaking change this pull requests involves in changing the PK is needed ASAP...