Bug 1838032

Description of problem:

When installing with user-provided-network feature (machinesSubnet), installer is selecting .1 address (or first address of the network, I am not sure) to connect to router.

If that address is already being used in the network, installer fails:

13:22:29  level=error msg="Error: Error creating openstack_networking_router_interface_v2: Expected HTTP response code [200] when accessing [PUT https://rhos-d.infra.prod.upshift.rdu2.redhat.com:13696/v2.0/routers/5e2baa2c-efcc-45d8-bed1-3eee0abe65f1/add_router_interface], but got 409 instead"
13:22:29  level=error msg="{\"NeutronError\": {\"message\": \"IP address 192.168.0.1 already allocated in subnet c8dcb634-ec20-43e2-8a8e-ea7ba3e4c3a7\", \"type\": \"IpAddressAlreadyAllocated\", \"detail\": \"\"}}"
13:22:29  level=error
13:22:29  level=error msg="  on ../../../../tmp/openshift-install-026215893/topology/private-network.tf line 140, in resource \"openstack_networking_router_interface_v2\" \"nodes_router_interface\":"
13:22:29  level=error msg=" 140: resource \"openstack_networking_router_interface_v2\" \"nodes_router_interface\" {"
13:22:29  level=error
13:22:29  level=error
13:22:29  level=fatal msg="failed to fetch Cluster: failed to generate asset \"Cluster\": failed to create cluster: failed to apply using Terraform"

Version-Release number of the following components:
rpm -q openshift-ansible
rpm -q ansible
ansible --version

How reproducible:

Steps to Reproduce:
1.Create a network and subnet on openstack, and use first address to create something
2.Install IPI on OSP with machinesSubnet pointing to that subnet

Actual results:
Installer fails because the address is on use

Expected results:
Installer select the IP address dynamically from a free one

Additional info:
Please attach logs from ansible-playbook with the -vvv flag