Only add SubscriptionConfigurationFilePaths if UseFederatedAuth is tr…

…ue (Azure#44742)

* Only add SubscriptionConfigurationFilePaths if UseFederatedAuth is true

* Fix up custom sub config in identity tests

eng/pipelines/templates/jobs/live.tests.yml

@@ -115,7 +115,9 @@ jobs:
           SubscriptionConfiguration: ${{ parameters.CloudConfig.SubscriptionConfiguration }}
           SubscriptionConfigurations: ${{ parameters.CloudConfig.SubscriptionConfigurations }}
           EnvVars: ${{ parameters.EnvVars }}
-          SubscriptionConfigurationFilePaths: ${{ parameters.CloudConfig.SubscriptionConfigurationFilePaths }}
+          ${{ if parameters.UseFederatedAuth }}:
+            SubscriptionConfigurationFilePaths: ${{ parameters.CloudConfig.SubscriptionConfigurationFilePaths }}
+
 
       - pwsh: |
           $project = "${{ parameters.Project }}"