Merged PR 5357: Adapt vr_check_in_cover model for Guest Products

# Description

This PR prepares the existing `int_core__vr_check_in_cover` model for the activation of the Guest Products feature flag.

It creates a second logic path which identifies VRs that have CIH in them ~~through product bundles~~ through looking at `stg_core__verification_request_to_guest_product `, and unions it with the old stuff.

The new CTE only gets called after the FF gets activated. This is defined in a var that we will need to adjust depending on when do we really activate the FF.

Note that these items are still pending:
- update the var to the right value once Lawrence pulls the trigger.
- clarify what the hell happens with CIH being "pushed" or not to ALL old dash hosts. This PR currently assumes this will NOT happen. If it will happen, we will need to change things.

# 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: #30165

models/intermediate/core/schema.yml

@@ -310,8 +310,14 @@ models:
           a first level of filtering.
 
   - name: int_core__vr_check_in_cover
-    description: "This tables holds information on verification requests
-      with Ckeck-in Hero available for the guests."
+    description: | 
+      This tables holds information on verification requests with Ckeck-in Hero
+      available for the guests.
+
+      The query has logic paths that cover both the Guest Products data model, 
+      which started on June 2025, and the previous "CIH is a verification step"
+      model.
+
     columns:
       - name: id_verification_request
         data_type: bigint