[CI/CD] Migrate to SONiC Elastictest (#15276)

Author: yejianquan

azure-pipelines.yml

@@ -77,7 +77,7 @@ stages:
   dependsOn: BuildVS
   condition: and(succeeded(), and(ne(stageDependencies.BuildVS.outputs['vs.SetVar.SKIP_VSTEST'], 'YES'), in(dependencies.BuildVS.result, 'Succeeded', 'SucceededWithIssues')))
   variables:
-  - group: Testbed-Tools
+  - group: SONiC-Elastictest
   - name: inventory
     value: veos_vtb
   - name: testbed_file