Merged PR 2232: KPI refactor - 1st step, bookings

First step on refactor of kpis:
- Remove relative incremental vs. previous year computation from the source model (`mtd_booking_metrics`, in this case)
- Aggregate the source mtd global metrics models into a single model: `int_mtd_vs_previous_year_metrics` (to enable multi-source weighted metric computation) and compute previous year value and relative increment. Now this logic is encapsulated into a macro `calculate_safe_relative_increment`, easing readability and providing a bit more robustness.
- End-to-end continuity to not break the existing dashboard display in `int_core__mtd_aggregated_metrics`

This is a substep of the global change. All info can be found in the documentation [here](https://www.notion.so/knowyourguest-superhog/Refactoring-Business-KPIs-5deb6aadddb34884ae90339402ac16e3)

Related work items: #18202

models/intermediate/core/int_core__mtd_aggregated_metrics.sql

@@ -1,6 +1,6 @@
 {% set metrics = [
     {
-        "source": "int_core__mtd_booking_metrics",
+        "source": "int_mtd_vs_previous_year_metrics",
         "order_by": 1,
         "metric": "Created Bookings",
         "value": "created_bookings",
@@ -9,7 +9,7 @@
         "number_format": "integer",
     },
     {
-        "source": "int_core__mtd_booking_metrics",
+        "source": "int_mtd_vs_previous_year_metrics",
         "order_by": 2,
         "metric": "Cancelled Bookings",
         "value": "cancelled_bookings",
@@ -18,7 +18,7 @@
         "number_format": "integer",
     },
     {
-        "source": "int_core__mtd_booking_metrics",
+        "source": "int_mtd_vs_previous_year_metrics",
         "order_by": 3,
         "metric": "Checkout Bookings",
         "value": "check_out_bookings",
@@ -190,8 +190,8 @@
     },
 ] %}
 with
-    int_core__mtd_booking_metrics as (
-        select * from {{ ref("int_core__mtd_booking_metrics") }}
+    int_mtd_vs_previous_year_metrics as (
+        select * from {{ ref("int_mtd_vs_previous_year_metrics") }}
     ),
     int_core__mtd_guest_journey_metrics as (
         select * from {{ ref("int_core__mtd_guest_journey_metrics") }}

models/intermediate/core/int_core__mtd_booking_metrics.sql

@@ -41,46 +41,19 @@ with
             and extract(day from b.updated_date_utc) <= d.day
             and upper(b.booking_state) = {{ var("cancelled_booking_state") }}
         group by 1
-    ),
-    main_kpi as (
-        -- Final aggregation of subqueries --
-        select
-            d.year,
-            d.month,
-            d.day,
-            d.date,
-            d.is_end_of_month,
-            d.is_current_month,
-            crym.created_bookings,
-            coym.check_out_bookings,
-            caym.cancelled_bookings
-        from int_dates_mtd d
-        left join created_year_month crym on crym.date = d.date
-        left join check_out_year_month coym on coym.date = d.date
-        left join cancelled_year_month caym on caym.date = d.date
     )
--- Pivoting to get previous year for each line & computing relative increment
--- (rel_incr) --
+-- Final aggregation of subqueries --
 select
-    a.year,
-    a.month,
-    a.day,
-    a.is_end_of_month,
-    a.is_current_month,
-    a.date,
-    b.date as previous_year_date,
-    a.created_bookings,
-    b.created_bookings as previous_year_created_bookings,
-    cast(a.created_bookings as decimal) / b.created_bookings
-    - 1 as relative_increment_created_bookings,
-    a.check_out_bookings,
-    b.check_out_bookings as previous_year_check_out_bookings,
-    cast(a.check_out_bookings as decimal) / b.check_out_bookings
-    - 1 as relative_increment_check_out_bookings,
-    a.cancelled_bookings,
-    b.cancelled_bookings as previous_year_cancelled_bookings,
-    cast(a.cancelled_bookings as decimal) / b.cancelled_bookings
-    - 1 as relative_increment_cancelled_bookings
-from main_kpi a
-left join main_kpi b on a.month = b.month and a.year = b.year + 1
-where (a.is_end_of_month = 1 or (a.is_current_month = 1 and a.day = b.day))
+    d.year,
+    d.month,
+    d.day,
+    d.date,
+    d.is_end_of_month,
+    d.is_current_month,
+    crym.created_bookings,
+    coym.check_out_bookings,
+    caym.cancelled_bookings
+from int_dates_mtd d
+left join created_year_month crym on crym.date = d.date
+left join check_out_year_month coym on coym.date = d.date
+left join cancelled_year_month caym on caym.date = d.date