Sync eng/common directory with azure-sdk-tools for PR 8528 (#30258)

Sync eng/common directory with azure-sdk-tools for PR
Azure/azure-sdk-tools#8528 See [eng/common
workflow](https://github.com/Azure/azure-sdk-tools/blob/main/eng/common/README.md#workflow)

---------

Co-authored-by: Ben Broderick Phillips <[email protected]>

Author: azure-sdk

eng/common/TestResources/build-test-resource-config.yml

@@ -8,14 +8,15 @@ parameters:
   # EnvVars is used to help diagnose variable conflict issues early
   - name: EnvVars
     type: object
-    default: null
+    default: {}
   - name: SubscriptionConfigurationFilePaths
     type: object
     default: null
 
 steps:
   - task: AzurePowerShell@5
     displayName: Set Pipeline Subnet Info
+    condition: ne(variables['Pool'], '')
     env: ${{ parameters.EnvVars }}
     inputs:
       azureSubscription: azure-sdk-tests