Description of problem:
Disable DHCP on a provider network after the creation didn't change the metadata information. 

Version-Release number of selected component (if applicable):
[rhosp-release] Red Hat OpenStack Platform release 16.1.6 GA (Train)
[os-release] Red Hat Enterprise Linux 8.2 (Ootpa) 8.2 (Ootpa)

Steps to Reproduce:
1. create a provider network with DHCP enabled
2. Disable DHCP on provider network
3. Launch an instance on this network, Openstack reserves an IP address in that network for the instance. However, the instance will never be reachable as it doesn't get its IP address configured. It didn't change if it is used config-drive or cloudinit for metadata propagation.

Actual results:
- In the case of the config drive, the network is labelled ipv4_dhcp:
~~~
  "networks": [
    {
      "id": "network0",
      "type": "ipv4_dhcp",
      "link": "tapxx-bf",
      "network_id": "xxx"
    }
~~
- In case of cloudinit, netplan:
~~~
network:
    ethernets:
        ens3:
            dhcp4: true
            match:
                macaddress: xxx
            set-name: ens3
    version: 2
~~~
However, the subnet to which these instances are attached has DHCP disabled:
~~~
$ openstack subnet show -f json xxx_subnet
{
  "allocation_pools": [
    {
      "start": "xxx",
      "end": "xxx"
    }
  ],
  "cidr": "xxx/21",
  "created_at": "2021-08-27T06:50:58Z",
  "description": "",
  "dns_nameservers": [
    "xxx",
    "xxx"
  ],
  "enable_dhcp": false,
  "gateway_ip": "xxx",
  "host_routes": [],
  "id": "xxx",
  "ip_version": 4,
  "ipv6_address_mode": null,
  "ipv6_ra_mode": null,
  "location": {
    "cloud": "",
    "region_name": "xxx",
    "zone": null,
    "project": {
      "id": "xxx",
      "name": "admin",
      "domain_id": null,
      "domain_name": "Default"
    }
  },
  "name": "xxx",
  "network_id": "xxx",
  "prefix_length": null,
  "project_id": "xxx",
  "revision_number": 1,
  "segment_id": null,
  "service_types": [],
  "subnetpool_id": null,
  "tags": [],
  "updated_at": "2021-09-27T09:40:15Z"
}
~~~

Expected results:
DHCP disable from metadata output