Merged PR 2583: Invoicing metrics per customer segmentation

# Description

Silly change:

* Modifies `int_core__mtd_guest_payments_metrics` to apply the proper key on date, dimension and dimension_value.
* -> *The weird thing is that the previous dbt test I run worked well. Is it possible that the configuration in the schema file prevails on top of the model configuration? I thought it was the other way around...*

Main changes:

* Modifies `int_xero__mtd_invoicing_metrics` to include the customer segmentation based on listings.
* `schema.yaml` is also affected including new fields and tests
* Added the macro to retrieve the production dimension in `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, Guest Journey, Deal, Accommodation and Guest Payments metrics. For reference, [here's the previous PR on Guest Payments](https://guardhog.visualstudio.com/Data/_git/data-dwh-dbt-project/pullrequest/2580).

This is the last PR on the source models for KPIs. Will follow: propagation + exposure

# Checklist

- [X] The edited models and dependants run properly with production data.
* **Important note**: this segmentation provides null values for all API-related KPIs. Makes sense, since the 4 deal id we have for APIs do NOT have, or have had, a listing linked to them. I'd say it's not a blocker.
- [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/xero/schema.yaml

@@ -291,10 +291,31 @@ 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 invoicing-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