Merged PR 3272: Expose Churn Rates into Main KPIs

# Description

Exposes Churn Rates into Main KPIs, specifically Revenue Churn Rate, Bookings Churn Rate and Listings Churn Rate. This is based on the average approach.

Additionally, it adds these 3 metrics in the kpis_additive_metrics_per_dimension_are_consistent test.
Additionally, it removes from int_mtd_vs_previous_year_metrics the computation of the additive Churn Rates. The removal of further unused code will be handled in a separated PR.

# Checklist

- [X] The edited models and dependants run properly with production data.
- [X] The edited models are sufficiently documented.
- [X] The edited models contain PK tests, and I've ran and passed them.
- [NA] I have checked for DRY opportunities with other models and docs.
- [NA] I've picked the right materialization for the affected models.

# Other

- [ ] Check if a full-refresh is required after this PR is merged.

Related work items: #22691

models/intermediate/cross/int_mtd_vs_previous_year_metrics.sql

@@ -161,9 +161,6 @@ with
             ) as total_revenue_per_listings_booked_in_month,
 
             -- CHURN --
-            churn.total_revenue_churn_additive_contribution,
-            churn.created_bookings_churn_additive_contribution,
-            churn.listings_booked_in_month_churn_additive_contribution,
             churn.total_revenue_churn_average_contribution,
             churn.created_bookings_churn_average_contribution,
             churn.listings_booked_in_month_churn_average_contribution
@@ -317,17 +314,6 @@ select
     }},
 
     -- CHURN --
-    {{ calculate_safe_relative_increment("total_revenue_churn_additive_contribution") }},
-    {{
-        calculate_safe_relative_increment(
-            "created_bookings_churn_additive_contribution"
-        )
-    }},
-    {{
-        calculate_safe_relative_increment(
-            "listings_booked_in_month_churn_additive_contribution"
-        )
-    }},
     {{ calculate_safe_relative_increment("total_revenue_churn_average_contribution") }},
     {{
         calculate_safe_relative_increment(