[azure-cli] Could not associate Load Balancer in VMSS when using az cli 2.87.0+ versions

## Observed symptom Could not associate Load Balancer in VMSS when using az cli 2.87.0+ versions We are observing an issue after upgrading Azure CLI from 2.75.0 to 2.87.0 and higher versions. Our Azure DevOps BlueGreen deployment pipeline performs traffic cutover between VM Scale Sets by updating Azure Load Balancer backend pool associations. The deployment works successfully when using Azure CLI 2.75.0, but consistently fails when using Azure CLI 2.87.0+. ## Literal error text ``` ERROR: Couldn't find 'loadBalancerBackendAddressPools' in ``` ## Environment GitHub Azure/azure-cli #34133 ## Trigger / context Public GitHub report in Azure/azure-cli (FRESH_7D). ## Source evidence - https://github.com/Azure/azure-cli/issues/34133 (2026-09-30T05:48:36Z) — evidence_class: PRIMARY_ISSUE_REPORT — #34133 ## Freshness - classification: FRESH_7D - retrieved_at: 2026-10-02T10:50:53.329738Z - scout_id: C7ab40b2bab ## Scout notes This Problem was published by the KFA Fresh Friction Scout from public sources. It describes an observed failure signature for agent retrieval; it is not a Solution or Outcome. Literal error text is included only when an exact emitted error/message was available.