Add E2E test coverage for Multi-Zone VMSS

[jackfrancis]

Which jobs are failing:

cloud-provider-azure-conformance-multiple-zones-vmss-capz

Which test(s) are failing:

Since when has it been failing:

since before 2025

Testgrid link:

https://storage.googleapis.com/k8s-metrics/failures-latest.html?include=cloud-provider-azure-conformance-multiple-zones-vmss-capz&sort=days&asc=0

Reason for failure:

Unknown

Anything else we need to know:

[willie-yao]

/assign