IPI Private cluster installation on Azure failed due to static IP not in range of subnet in RHOCP4

Issue

• Deploying an Azure IPI RHOCP cluster in a disconnected environment is failing with the following error:

  time="xxxx-xx-xxx" level=fatal msg="failed to fetch Cluster: failed to fetch dependency of \"Cluster\": failed to generate asset \"Cluster API Manifests\": failed to generate Azure manifests: failed to get azure ip availability: network.VirtualNetworksClient#CheckIPAddressAvailability: Failure responding to request: StatusCode=400 -- Original Error: autorest/azure: Service returned an error. Status=400 Code=\"PrivateIPAddressNotInAnySubnet\" Message=\"Private static IP address xx.x.x.xxx does not belong to the range of any subnet in the virtual network /subscriptions/<subscription_id>/resourceGroups/<nsg_name>/providers/Microsoft.Network/virtualNetworks/<nw_name>\" Details=[]"