roachprod: support Geo Zones for Azure.

Currently Azure does not support creating geo-distributed clusters. There is existing infra to declare zones, but it runs into issues when creating zones that have overlapping address spaces, i.e. `eastus` and `westus`, which we commonly do in multiregion tests.

Trying to do so returns the following error:

> Code="VnetAddressSpaceOverlapsWithAlreadyPeeredVnet" Message="Cannot create or update peering /subscriptions/73075e4f-150d-4f4f-956b-053507b61fa7/resourceGroups/roachprod-vnets-eastus/providers/Microsoft.Network/virtualNetworks/roachprod-vnets-eastus/virtualNetworkPeerings/roachprod-vnets-eastus-roachprod-vnets-westus3. Virtual networks /subscriptions/73075e4f-150d-4f4f-956b-053507b61fa7/resourceGroups/roachprod-vnets-westus3/providers/Microsoft.Network/virtualNetworks/roachprod-vnets-westus3 and /subscriptions/73075e4f-150d-4f4f-956b-053507b61fa7/resourceGroups/roachprod-vnets-eastus/providers/Microsoft.Network/virtualNetworks/roachprod-vnets-eastus cannot be peered because address space of the first virtual network overlaps with address space of virtual network /subscriptions/73075e4f-150d-4f4f-956b-053507b61fa7/resourceGroups/roachprod-vnets-westus2/providers/Microsoft.Network/virtualNetworks/roachprod-vnets-westus2 already peered with the second virtual network. Overlapping address prefixes: 10.2.0.0/16. For more information please refer to https://aka.ms/VnetPeeringInfo" Details=[])

The issue should be investigated and fixed so we can support Geo Zones in Azure and enable multiregion tests.

Jira issue: CRDB-38977