Merged PR 2533: Guest Journey metrics per customer segmentation

# Description

Modifies `int_core__mtd_guest_journey_metrics` to include the customer segmentation based on listings. `schema.yaml` is also affected including new fields and tests. Hardcoded `int_core__mtd_vs_previous_year_metrics` to avoid propagating this upwards and messing up with the data display.

Overall, follows a similar strategy as we did for Booking metrics.

# 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.
- [X] I have checked for DRY opportunities with other models and docs.
- [X] 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: #19325

models/intermediate/core/schema.yaml

@@ -262,13 +262,34 @@ models:
       It's used for the business KPIs. Data is aggregated at the last day of the month and in the
       days necessary for the Month-to-Date computation of the current month.
 
+    tests: 
+      - dbt_utils.unique_combination_of_columns:
+          combination_of_columns:
+            - date
+            - dimension
+            - dimension_value
+            
     columns:
       - name: date
         data_type: date
         description: The date for the month-to-date guest journey-related metrics.
         tests:
           - not_null
-          - unique
+
+      - name: dimension
+        data_type: string
+        description: The dimension or granularity of the metrics.
+        tests:
+          - accepted_values:
+                values:
+                - global
+                - by_number_of_listings
+      
+      - name: dimension_value
+        data_type: string
+        description: The value or segment available for the selected dimension.
+        tests:
+          - not_null
 
   - name: int_core__mtd_accommodation_metrics
     description: |