[reproducer] Fix MAC address corruption in bm_info

The `_with_nics` variable already evaluates to a Python dict from
the `combine()` call. Piping it through `| from_yaml` caused Ansible
to serialize it as a YAML string and re-parse it.

PyYAML's YAML 1.1 sexagesimal rule then corrupted **all-numeric** MAC
addresses (e.g. `41:13:61:22:00:02`) into integers (`41136122002`).

Remove the redundant `| from_yaml` to prevent the lossy round-trip.

Closes: OSPRH-31852
Assisted-By: Claude (claude-4.6-sonnet-medium)
Signed-off-by: Harald Jensås <hjensas@redhat.com>

Author: hjensas

roles/reproducer/tasks/generate_bm_info.yml

@@ -108,7 +108,7 @@
     libvirt_manager_bm_info_data: >-
       {{
         libvirt_manager_bm_info_data | default({}) |
-        combine((_with_nics | from_yaml), recursive=true) |
+        combine(_with_nics, recursive=true) |
         combine((_oringal_cifmw_baremetal_hosts | default({}) | from_yaml), recursive=true)
       }}
   loop: "{{ cifmw_libvirt_manager_uuids | dict2items }}"