proxy12: fix mac address

This had the hard coded mac address of the previous vm.
We moved to using ansible to just fill in the current mac, so fix that
here too.

Signed-off-by: Kevin Fenzi <kevin@scrye.com>

inventory/host_vars/proxy12.fedoraproject.org

@@ -15,7 +15,6 @@ has_ipv4: yes
 has_ipv6: yes
 ks_repo: https://infrastructure.fedoraproject.org/pub/fedora/linux/releases/44/Server/x86_64/os/
 ks_url: https://infrastructure.fedoraproject.org/repo/rhel/ks/kvm-fedora
-mac0: "52:54:00:84:5d:9f"
 main_bridge: br0
 max_mem_size: 20000
 mem_size: 16384
@@ -35,7 +34,7 @@ network_connections:
         - "{{ dns_search2 }}"
       gateway4: "{{ eth0_ipv4_gw }}"
       gateway6: "{{ eth0_ipv6_gw }}"
-    mac: "{{ mac0 }}"
+    mac: "{{ ansible_default_ipv4.macaddress }}"
     name: eth0
     type: ethernet
 nrpe_procs_crit: 1400