[Feature] amazon_ads__portfolio_report should be downstream int_amazon_ads__portfolio_history

### Is there an existing feature request for this?

- [X] I have searched the existing issues

### Describe the Feature

[int_amazon_ads__portfolio_history](https://github.com/fivetran/dbt_amazon_ads/blob/main/models/intermediate/int_amazon_ads__portfolio_history.sql) was created to generate an empty table if the source `portfolio_history` table is disabled. It is brought into most end models, example [here](https://github.com/fivetran/dbt_amazon_ads/blob/d9b18cf4d77c517dcfcebee3a66b7b917d7c1186/models/amazon_ads__campaign_report.sql#L16) and [here](https://github.com/fivetran/dbt_amazon_ads/blob/d9b18cf4d77c517dcfcebee3a66b7b917d7c1186/models/amazon_ads__search_report.sql#L16), however it is not brought into [amazon_ads__portfolio_report](https://github.com/fivetran/dbt_amazon_ads/blob/main/models/amazon_ads__portfolio_report.sql) itself.

To keep `amazon_ads__portfolio_report` consistent and reduce confusion with the other models, suggest to update it to reference the int model. This would also benefit the lineage graph in the docs.

### Describe alternatives you've considered

_No response_

### Are you interested in contributing this feature?

- [X] Yes.
- [ ] Yes, but I will need assistance and will schedule time during your [office hours](https://calendly.com/fivetran-solutions-team/fivetran-solutions-team-office-hours) for guidance.
- [ ] No.

### Anything else?

_No response_