relax test that didn't make sense, revert wrong solution to issue from this morning

models/intermediate/core/int_core__guest_product_payments_v2.sql

@@ -131,7 +131,7 @@ with
             = vrtgp.id_verification_request_to_guest_product
         left join
             int_core__guest_products gp on vrtgp.id_guest_product = gp.id_guest_product
-        inner join
+        left join
             stg_core__verification_request vr
             on vrtgp.id_verification_request = vr.id_verification_request
     )

models/intermediate/core/schema.yml

@@ -5579,9 +5579,7 @@ models:
         description: |
           Unique identifier of the Guest linked to the Verification 
           Request that has a payment. 
-          It cannot be null.
-        data_tests:
-          - not_null
+          It can be null if the guest has not yet logged into Truvi at all.
 
       - name: id_verification_request
         data_type: bigint