Centralize the logic that looks at the latest organic traffic data and computes CPC

**Is your feature request related to a problem? Please describe.**
Related to: https://github.com/adobe/spacecat-audit-worker/pull/725

**Describe the solution you'd like**
In the future, we'll have to centralize the logic that looks at the latest organic traffic data and computes CPC, as this is now also in https://github.com/adobe/spacecat-api-service/blob/e0e3d1e2310636055b037d24d8ddc038114e31bb/src/controllers/sites.js#L423-L439 and https://github.com/adobe/spacecat-import-worker/blob/e0ae0953ae33aac5775a7e2a9a5d954553f35a36/src/mapper/latest-metrics.js#L30-L35

Compara la lógica referenciada en spacecat-api-service/src/controllers/sites.js alrededor de las líneas 423-439 y en spacecat-import-worker/src/mapper/latest-metrics.js alrededor de las líneas 30-35, junto con el pull request relacionado de spacecat-audit-worker. Determina el punto de entrada compartido y los consumidores esperados antes de definir qué incluirían una implementación centralizada y una migración completada.

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