Fix dynamic resource provisioning for live Cosmos tests (#11256)

* set global SubscriptionConfiguration

* add default value to $(SubscriptionConfiguration)

* set $(SubscriptionConfiguration) at the template job's level

Author: danieljurek

eng/pipelines/templates/jobs/archetype-sdk-tests.yml

@@ -61,6 +61,10 @@ jobs:
 
     variables:
       - template: ../variables/globals.yml
+      # Default $(SubscriptionConfiguration) if the matrix does not specify a $(SubscriptionConfiguration)
+      - name: SubscriptionConfiguration
+        value: $(sub-config-azure-cloud-test-resources)
+
     strategy:
       matrix: ${{ parameters.Matrix }}
       maxParallel: ${{ parameters.MaxParallel }}