macvlan network option metric doesn't change the metric with dhcp

Hello

OS: `Linux pi5 6.6.47-3-rpi containers/common#1 SMP PREEMPT Sat Aug 31 07:27:25 MDT 2024 aarch64 GNU/Linux`
Podman version: `5.2.2-1`
Netavark version: `1.12.2-1`

Preamble from related issue containers/common#2051 is identical:
> I have a container attached to multiple macvlan networks. As some of the networks block access to the internet, my container sometimes can't access the internet as all routes have a default metric of 100.

I can now create a network with the `metric` option, which is great! However, it doesn't seem to take effect inside the container.

Background: There's 3 network interfaces on the host, one physical `end0` and two vlan `end0.100`, `end0.200`. The vlan interfaces have metrics and `end0.200` doesn't have a default gateway. All interfaces use DHCP.

```bash
$ id
uid=0(root) gid=0(root) groups=0(root)
```

```bash
$ ip route
default via 192.168.1.1 dev end0 proto dhcp src 192.168.1.101
default via 172.21.100.1 dev end0.100 proto dhcp src 172.21.100.101 metric 768
192.168.1.0/24 dev end0 proto kernel scope link src 192.168.1.101
172.21.100.0/24 dev end0.100 proto kernel scope link src 172.21.100.101 metric 768
172.31.200.0/24 dev end0.200 proto kernel scope link src 172.31.200.101 metric 1024
[...]
```

Creating the network with 3 different metric options (`podman network inspect` shows metric under options):

```bash
$ podman network create --driver macvlan --interface-name=end0 --ipam-driver=dhcp \
--opt=metric=50 foo1
foo1
$ podman network create --driver macvlan --interface-name=end0.100 --ipam-driver=dhcp \
--opt=metric=150 foo2
foo2
$ podman network create --driver macvlan --interface-name=end0.200 --ipam-driver=dhcp \
--opt=metric=250 foo3
foo3
```

Running a container attached to all 3 networks:

```bash
$ podman run -ti --rm \
"--network=foo3:mac=ba:d6:d5:c7:e6:7b" \
"--network=foo2:mac=a6:87:e2:04:61:97" \
"--network=foo1:mac=42:d3:60:fd:a8:92" \
--entrypoint /bin/sh \
docker.io/busybox:latest
```

Inside the container the metric is still `100`:

```bash
/ # ip route
default via 192.168.1.1 dev eth2 metric 100
default via 172.21.100.1 dev eth1 metric 100
192.168.1.0/24 dev eth2 scope link src 192.168.1.209
172.21.100.0/24 dev eth1 scope link src 172.21.100.201
172.31.200.0/24 dev eth0 scope link src 172.31.200.203
/ #
```

I'm expecting `192.168.1.1`'s metric to be `50` (`end0`) and `172.21.100.1`'s metric to be `150` (`end0.100`).

For more information on package versions and `podman info` please see [attached](https://github.com/user-attachments/files/16884092/versions-2024-09-04.txt).

Thanks!